U.S. patent number 5,130,603 [Application Number 07/490,337] was granted by the patent office on 1992-07-14 for organic electroluminescence device.
This patent grant is currently assigned to Idemitsu Kosan Co., Ltd.. Invention is credited to Hisahiro Higashi, Chishio Hosokawa, Hiroshi Tokailin.
United States Patent |
5,130,603 |
Tokailin , et al. |
July 14, 1992 |
**Please see images for:
( Certificate of Correction ) ** |
Organic electroluminescence device
Abstract
An electroluminescence device comprising, as a light emitting
material, a compound of the formula: ##STR1## wherein R.sup.1 and
R.sup.2 are each an alkyl, cyclohexyl, alkoxy, cyano or aryl,
R.sup.3 and R.sup.4 are a heterocyclic or aryl and Ar is an
arylene. Aromatic dimethylidyne compounds of the formula: ##STR2##
wherein X and Y are each an alkyl, phenyl, cyclohexyl, naphthyl or
pyridyl and Ar' is ##STR3## Electroluminescence devices (EL
devices) using the above compounds as a light emitting material
provide EL light emission of high luminance in a region of bluish
purple to green.
Inventors: |
Tokailin; Hiroshi (Sodegaura,
JP), Higashi; Hisahiro (Sodegaura, JP),
Hosokawa; Chishio (Sodegaura, JP) |
Assignee: |
Idemitsu Kosan Co., Ltd.
(Tokyo, JP)
|
Family
ID: |
26409618 |
Appl.
No.: |
07/490,337 |
Filed: |
March 8, 1990 |
Foreign Application Priority Data
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|
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Mar 20, 1989 [JP] |
|
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1-68387 |
Dec 28, 1989 [JP] |
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1-338134 |
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Current U.S.
Class: |
313/504;
252/301.16; 428/917; 585/25 |
Current CPC
Class: |
C07C
13/28 (20130101); C07C 15/52 (20130101); C07C
15/58 (20130101); C07C 15/60 (20130101); C07C
43/215 (20130101); C09K 11/06 (20130101); H01L
51/005 (20130101); H01L 51/0052 (20130101); H01L
51/0059 (20130101); H01L 51/0062 (20130101); H01L
51/0067 (20130101); H05B 33/14 (20130101); H01L
51/0053 (20130101); H01L 51/007 (20130101); H01L
51/5012 (20130101); H01L 2251/308 (20130101); Y10S
428/917 (20130101); C07C 2601/14 (20170501) |
Current International
Class: |
C07C
15/00 (20060101); C07C 15/52 (20060101); C09K
11/06 (20060101); H01L 51/30 (20060101); H01L
51/05 (20060101); H05B 33/14 (20060101); H01L
51/50 (20060101); H01J 001/63 (); C09K
011/06 () |
Field of
Search: |
;313/504 ;427/66
;428/917 ;585/25 ;252/301.16 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0281381 |
|
Sep 1988 |
|
EP |
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0319881 |
|
Jun 1989 |
|
EP |
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63-269158 |
|
Nov 1988 |
|
JP |
|
64-25479 |
|
Oct 1989 |
|
JP |
|
Other References
Takeda et al.: "Kioku, Kiroku, Kankozairyo", edited by Gakkai
Shuppan-Center, Jan. 30, 1988, pp. 161 and 162, Mechanism of
Electrophoto-Sensitive Material, and partial English language
translation thereof. .
C. W. Tang et al., "Organic Electroluminescent Diodes", Appl. Phys.
Lett., 51, Sep. 21, 1987, pp. 913 to 915, 1987. .
P. S. Vincett et al., "Electrical Conduction and Low Voltage Blue
Electroluminescence in Vacuum-Deposited Organic Films", Thin Solid
Films, 94, (1982), 174-183. .
W. Helfrich et al., "Transients of Volume-Controlled Current and of
Recombination Radiation in Anthracene", vol. 44, No. 8, Apr. 15,
1966, pp. 2902-2909, The Journal of Chemical Physics..
|
Primary Examiner: Willis, Jr.; Prince
Assistant Examiner: Steinberg; Thomas
Attorney, Agent or Firm: Frishauf, Holtz, Goodman &
Woodward
Claims
What is claimed is:
1. An electroluminescence device comprising a light emitting
material placed between a pair of electrodes, wherein the light
emitting material comprises a compound represented by the formula:
##STR53## wherein R.sup.1 and R.sup.2 are each an alkyl group, an
unsubstituted cyclohexyl group; a cyclohexyl group substituted by
at least one substituent selected from the group consisting of an
alkyl group, an alkoxy group, or a phenyl group; an alkoxy group; a
cyano group; an unsubstituted aryl group; an aryl group substituted
with at least one substituent (a) selected from the group
consisting of an alkyl group, an alkoxy group, an acyl group, an
acyloxy group, an acyl amino group, an aralkyl group, an aryloxy
group, a cyano group, a carboxyl group, a vinyl group, a styryl
group, an aminocarbonyl group, an aryloxycarbonyl group, a hydroxyl
group, an alkoxycarbonyl group, a halogen group and an amino group,
wherein the substituents together may form a 5-membered or
6-members ring; R.sup.3 and R.sup.4 are each an unsubstituted
heterocyclic group, a heterocyclic group substituted by at least
one substituent (a) as defined above, an unsubstituted aryl group
or aryl group substituted by at least one substituent (a) as
defined above, Ar is an unsubstituted arylene group or an arylene
group substituted by a substituent selected from the group a cyano
group, a carboxyl group, an aminocarbonyl group, a carbamoyl group,
an aranyl group, a hydroxyl group, an aryloxycarbonyl group, a
methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl
group and an amino group, wherein the substituents together may
form a saturated 5-members or 6-membered ring, and R.sup.1 and
R.sup.3, and R.sup.2 and R.sup.4 may combine together to form a
saturated or unsaturated ring structure.
2. The electroluminescence device as claimed in claim 1, wherein
the compound is represented by the formula: ##STR54## wherein X and
Y may be the same or different and are each an alkyl group having 1
to 4 carbon atoms, a phenyl group, a substituted phenyl group, a
cyclohexyl group, a substituted cyclohexyl group, a naphthyl group,
a substituted naphthyl group, a pyridyl group or a substituted
pyridyl group, wherein the substituted phenyl group, the
substituted cyclohexyl group, the substituted naphthyl group and
the substituted pyridyl group are substituted by a substituent
which is an alkoxy group having 1 to 4 carbon atoms, an alkoxy
group having 1 to 4 carbon atoms, or a phenyl group, and each
substituted group may be substituted by a plurality of said
substituent groups, and Ar' is ##STR55##
3. The electroluminescence device as claimed in claim 2 wherein X
and Y are each a methyl group, a naphthyl group, a pyridyl group, a
cyclohexyl group, a tolyl group, a methoxyphenyl group, or a
biphenyl group.
4. The electroluminescence device as claimed in claims 1 or 2,
further comprising laminated in the following order: a positive
electrode, a hole injection layer, a light emitting layer
comprising said light emitting material, and a negative
electrode.
5. The electroluminescence device as claimed in claims 1 or 2
further comprising laminated in the following order a positive
electrode, a hole injection layer, a light emitting layer
comprising said light emitting material, an electron injection
layer, and a negative electrode.
6. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR56##
7. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR57##
8. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR58##
9. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR59##
10. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR60##
11. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR61##
12. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR62##
13. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR63##
14. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR64##
15. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR65##
16. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR66##
17. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR67##
18. The electroluminescence device as claimed in claim 2, wherein
said compound is ##STR68##
19. The electroluminescence device as claimed in claim 1, wherein
the electrode are electrode layers.
20. The electroluminescence device as claimed in claim 4, further
comprising an electron injection layer disposed between the light
emitting layer and the negative electrode.
21. The electroluminescence device as claimed in claim 5, further
comprising an electron injection layer disposed between the light
emitting layer and the negative electrode.
22. The electroluminescence device as claimed in claim 1, wherein
Ar is a phenylene group or a biphenylene group.
23. An electroluminescence device as claimed in claim 1, wherein
R.sup.1 and R.sup.2 are each a methyl group; and ethyl group; a
propyl group; a butyl group; an unsubstituted cyclohexyl group; a
cyclohexyl group substituted by at least one substituent selected
from the group consisting of an alkyl group having 1 to 4 carbon
atoms, an alkoxy group having 1 to 4 carbon atoms and a phenyl
group; a methoxy group; an ethoxy group; a propoxy group; a butoxy
group; a cyano group; an unsubstituted phenyl; an unsubstituted
naphthyl; an unsubstituted anthranyl; or a phenyl, naphthyl or
anthranyl group substituted by a substituent (a) selected from the
group consisting of a halogen atom, an ethyl group, a propyl group,
a butyl group, a methoxy group, an ethoxy group, a propoxy group, a
butoxy group, a formyl group, a propionyl group, a butylyl group,
an acetyloxy group, a propionylamino group, a butylylamino group, a
phenoxy group, a tolyloxy group, a cyano group, a carboxyl group, a
vinyl group, a styryl group, an anilinocarbonyl group, a
dimethylamonocarbonyl group, a carbamoyl group, an aranyl group, a
hydroxyl group, a naphthyloxycarbonyl group, a xylyloxycarbonyl
group, a phenoxycarbonyl group, a methoxycarbonyl group, an
ethoxycarbonyl group, a butoxycarbonyl group, and an amino group
represented by the formula: ##STR69## wherein R.sup.5 and R.sup.4
are each a hydrogen atom, a methyl group, an ethyl group, a propyl
group or a butyl group, a formyl group, a propionyl group, an
aldehyde group, an unsubstituted phenyl group, a tolyl group, a
xylyl group, or R.sup.5 and R.sup.6 together form a 5-membered or
6-membered ring,
R.sup.3 and R.sup.4 are each an unsubstituted phenyl, unsubstituted
naphthyl, unsubstituted anthranyl, unsubstituted pyridyl group,
unsubstituted oxazolyl group, unsubstituted thienyl group,
unsubstituted imidazolyl group, unsubstituted thiazolyl group,
unsubstituted benzoimidazolyl group, unsubstituted benzothiazolyl
group, unsubstituted pyrazolyl group, unsubstituted triazolyl
group, unsubstituted monovalent group comprising pyridone,
unsubstituted furaryl group, unsubstituted benzoxazolyl group, or
unsubstituted quinolyl group, or a phenyl, naphthyl, anthranyl, a
pyridyl group, an oxazolyl group, a thienyl group, an imidazolyl
group, a thiazolyl group, a benzoimidazolyl group, a benzothiazolyl
group, a pyrazolyl group, a triazolyl group, a monovalent group
comprising pyridone, a furaryl group, a benzoxazolyl group, or a
quinolyl group substituted by one or more of said substituents
(a),
Ar is an unsubstituted arylene group or an arylene group
substituted by a halogen atom, a methyl group, an ethyl group, a
propyl group, a butyl group, a cyclohexyl group, a methoxy group,
an ethoxy group, a propoxy group, a butoxy group, a formyl group, a
propionyl group, a butyryl group, an acetyloxy group, a
propionylamino group, a butylylamino group, a benzyl group, a
phenethyl group, a phenoxy group, a tolyloxy group, a cyano group,
a carboxyl group, an anilinocarbonyl group, a dimethylamonocarbonyl
group, a carbamoyl group, an aranyl group, a hydroxyl group, a
phenoxycarbonyl group, a naphthyloxycarbonyl group, a
xylyloxycarbonyl group, a methoxycarbonyl group, an ethoxycarbonyl
group, a butoxycarbonyl group, and an amino group of said formula
(I).
24. The electroluminescence device as claimed in claim 2, wherein X
and Y are the same or different and each is a methyl, ethyl,
n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl,
unsubstituted phenyl, unsubstituted cyclohexyl, unsubstituted
naphthyl or unsubstituted pyridyl, tolyl, dimethylphenyl,
ethylphenyl, methoxyphenyl, ethoxyphenyl, biphenyl,
methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl,
methoxycyclohexyl, ethoxycyclohexyl, phenylcyclohexyl,
methylnaphthyl, dimethylnaphthyl, methoxynaphthyl, ethoxynaphthyl,
methyl pyridyl, phenyl-unsubstituted naphthyl, dimethylpyridyl,
ethylpyridyl, methoxypyridyl, ethoxypyridyl or phenyl-substituted
pyridyl.
25. An electroluminescence device comprising a light emitting
material placed between a pair of electrodes wherein the light
emitting material comprises a compound represented by the formula:
##STR70## wherein R.sup.1 and R.sup.2 are each an alkyl group, a
cyclohexyl group; an alkoxy group; a cyano group; an unsubstituted
aryl group; an aryl group substituted with at least one substituent
(a) selected from the group consisting of an alkyl group, an alkoxy
group, an acyl group, an acyloxy group, an acyl amino group, an
aralkyl group, an aryloxy group, a cyano group, a carboxyl group, a
vinyl group, a styryl group, an aminocarbonyl group, an
aryloxycarbonyl group, a hydroxyl group, an alkoxycarbonyl group, a
halogen group and an amino group, wherein the substituents together
may form a 5-membered or 6-members ring; R.sup.3 and R.sup.4 are
each an unsubstituted heterocyclic group, a heterocyclic group
substituted by at least one substituent (a) as defined above, an
unsubstituted aryl group or aryl group substituted by at least one
substituent (a) as defined above, Ar is an unsubstituted arylene
group or an arylene group substituted by a substituent selected
from the group consisting of a halogen atom, an alkyl group, an
alkoxy group, an acyl group, an acyloxy group, an aralkyl group, an
aryloxy group, a cyano group, a carboxyl group, an aminocarbonyl
group, a carbamoyl group, an aranyl group, a hydroxyl group, an
aryloxycarbonyl group, a methoxycarbonyl group, an ethoxycarbonyl
group, a butoxycarbonyl group and an amino group, wherein the
substituents together may form a saturated 5-members or 6-membered
ring, and R.sup.1 and R.sup.3, and R.sup.2 and R.sup.4 may combine
together to form a saturated or unsaturated ring structure.
26. The electroluminescence device as claimed in claim 1, wherein
the compound is selected from the group consisting of ##STR71##
27. The electroluminescence device as claimed in claim 1, wherein
the compound is represented by the formula: ##STR72## wherein X and
Y may be the same or different and are each an alkyl group having 1
to 4 carbon atoms, a phenyl group, a substituted phenyl group, a
cyclohexyl group, a substituted cyclohexyl group, a naphthyl group,
a substituted naphthyl group, a pyridyl group or a substituted
pyridyl group, wherein the substituted phenyl group, the
substituted cyclohexyl group, the substituted naphthyl group and
the substituted pyridyl group are substituted by a substituent
which is an alkoxy group having 1 to 4 carbon atoms, an alkoxy
group having 1 to 4 carbon atoms, or a phenyl group, and each
substituted group may be substituted by a plurality of said
substituent groups, and Ar' is ##STR73##
28. The electroluminescence device as claimed in claim 27, wherein
said compound is ##STR74##
29. The electroluminescence device as claimed in claim 27, wherein
said compound is ##STR75##
30. The electroluminescence device as claimed in claim 27, wherein
said compound is ##STR76##
31. The electroluminescence device as claimed in claim 27, wherein
said compound is ##STR77##
32. The electroluminescence device as claimed in claim 27, wherein
said compound is ##STR78##
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel electroluminescence (EL)
device and more particularly to an organic EL device capable of
emitting light in a region of bluish purple to green at a high
luminance and in a stabilized manner. Moreover, the present
invention relates to novel aromatic dimethylidyne compounds useful,
for example, as emitting materials for an EL device, processes for
efficiently preparing the above compounds, and an EL device using
the above compound.
2. Description of the Related Arts
A device utilizing EL performance of an organic compound has been
long studied in view of fluorescence of the organic compound. For
example, W. Helfrish, Dresmer, Williams et al. succeeded in
emission of blue light using anthracene crystal (J. Chem. Phys. 44,
2902 (1966)). Vincett, Barlow, et al. produced a light emitting
device by a vapor deposition method, using a condensed polycyclic
aromatic compound (Thin Solid Films, 94, 171 (1982)).
However, only a light emitting device low in luminance and luminous
efficiency has been obtained.
It is reported that emission of blue light of 100 cd/m.sup.2 was
obtained using tetraphenylbutadiene as a light emitting material
(Japanese Patent Application Laid-Open No. 194393/1984). In
practice, however, the efficiency is markedly low and is
unsatisfactory.
It is reported that a green light emitting organic thin film EL
device providing the maximum luminance of more than 1,000
cd/m.sup.2 and an efficiency of 1 lm/W was developed by laminating
a diamine compound conveying a hole and a luminous aluminum chelate
complex as a light emitting material (Appl. Phys. Lett., 51, 913
(1987)).
It is also reported that a distyrylbenzene compound well known as a
laser dye exhibits high fluorescent properties in the region of
blue to blue green, and a light emitting material using the
distyrylbenzene compound in a single layer form emits EL light of
about 80 cd/m.sup.2 (European Patent 0319881).
However, a light emitting material providing light other than green
light (particularly blue-based light) in a luminance as high as
more than 1,000 cd/m.sup.2 and with high efficiency has not been
obtained.
In connection with the structure of the aforementioned organic EL
device, those obtained by properly providing a hole injection layer
or an electron injection layer into a basic structure having a
positive electrode/light emitting layer/negative electrode, e.g., a
structure of positive electrode/hole injection layer/light emitting
layer/negative electrode, or a structure of positive electrode/hole
injection layer/light emitting layer/electron injection
layer/negative electrode are known. The hole injection layer
functions to inject a hole into the light emitting layer from the
positive electrode, and the electron injection layer, to inject an
electron into the light emitting layer from the negative electrode.
It is known that placing the hole injection layer between the light
emitting layer and the positive electrode permits injection of more
holes at a lower voltage, and that electrons injected from the
negative electrode or the injection layer into the light emitting
layer are accumulated at the light emitting layer side in an
interface between the light emitting layer and the hole injection
layer when the hole injection layer does not have electron
transporting ability, increasing a luminous efficiency (Applied
Physics Letters, Vol. 51, p. 913 (1987)).
As such organic EL devices, for example, (1) a laminate type EL
device having a structure of positive electrode/hole injection
layer/light emitting layer/negative electrode in which the light
emitting layer is made of an aluminum complex of
8-hydroxyquinoline, and the hole injection layer, of a diamine
compound (Appl. Phys. Lett., Vol. 51, p. 913 (1987)), (2) a
laminate type EL device having a structure of positive
electrode/hole injection zone/organic light emitting zone/negative
electrode in which an aluminum complex of 8-hydroxyquinoline is
used in preparation of the light emitting zone (Japanese Patent
Application Laid-Open No. 194393/1984), and (3) an EL device having
a structure of positive electrode/hole injection zone/light
emitting zone/negative electrode in which the light emitting zone
is made of a host material and a fluorescent material (European
Patent Publication No. 281381) are known.
In the above EL devices (1) and (2), although light emission of
high luminance is attained at a low voltage, it is necessary to
control the temperature of a vapor deposition source not to be more
than 300.degree. C., i.e., as low as nearly an evaporation
temperature in vapor deposition, because an aluminum complex of
8-hydroxyquinoline when used as a light emitting material is
readily decomposable at a temperature of more than about
300.degree. C. It is therefore difficult to control conditions for
production of a device and, moreover, vapor deposition speed is
decreased. Thus the devices (1) and (2) inevitably suffer from a
problem of a reduction in productivity of devices. Moreover the
aluminum complex of 8-hydroxyquinoline can emit green light, but
not blue light.
In the EL device (3), a compound capable of injecting a hole and a
electron from the outside, preferably an aluminum complex of
8-hydroxyquinoline is used as a host material, and as a fluorescent
material, a compound capable of emitting light in response to
re-combination of a hole and an electron, such as a known
fluorescent dye.
In this device, among an injection function (function to inject a
hole from either a positive electrode or a hole injection layer and
also to inject an electron either from an electrode or a negative
electron injection layer, upon application of electric field), a
transport function (function to transport a hole and an electron
upon application of electric field), and a light emitting function
(function to provide a field for recombination of a positive hole
and an electron, thereby producing light emission), the light
emitting zone (light emitting layer) should have the injection
function, the transport function, and part of the light emitting
function fulfilled by the host material, while only part of the
light emitting function is fulfilled by the fluorescent material.
For this reason, the host material is doped with a very small
amount (not more than 5 mol %) of the fluorescent material. An EL
device of the above structure can emit light in the region of from
green to red at a luminance as high as above 1,000 cd/m.sup.2 by
application of a voltage of about 10 V.
In this EL device, however, the same problems as in the above EL
devices (1) and (2) are encountered, because it usually uses
8-hydroxyquinoline-Al complex as a host material. Moreover, it is
impossible to emit light of a short wavelength having a higher
energy than the energy gap value of the 8-hydroxyquinone from a
fluorescent material; emission of blue light cannot be
obtained.
As described above, the above devices (1), (2) and (3) cannot
provide blue light emission of high luminance in a stabilized
manner and with high efficiency. However, they provides an epoch
making technical advance by showing that a high luminous and high
efficiency EL device can be realized by selecting a light emitting
material with a structure of positive electrode/hole injection
layer made of amino derivative/light emitting layer/negative
electrode. In this selection of the light emitting material, the
three functions of the above light emitting layer should be
satisfied. Moreover it should be taken into consideration that a
material with excellent film forming properties as a light emitting
layer should be selected. Moreover the material selected should
have excellent heat resistance properties and should avoid
decomposition at the time of heating for vacuum deposition. It has
been difficult to find a light emitting material to satisfy all the
above requirements. Thus the present inventors made extensive
investigations to develop a compound providing light emission in a
region of bluish purple to green, particularly in a blue region at
a high luminance and with high efficiency.
The present inventors made extensive investigations to attain the
above objects. As a result, they have found that stilbene-based
compounds having specified structures have an injection ability, a
transporting ability and a light emitting ability essential for a
light emitting layer, are excellent in heat resistance and thin
film forming properties, are free from decomposition even if heated
to a vacuum deposition temperature, can form a uniform and dense
film having excellent thin film forming properties, and moreover
are rarely subject to formation of pinholes at the time of
formation of the opposite electrode (metal), and that if the above
compounds are used as light emitting materials, an EL device can be
obtained with high efficiency and moreover the EL device provides
stable light emission of high luminance from bluish purple to green
upon application of a low voltage. Based on the findings, these
present invention has been accomplished. Furthermore, the EL device
is of high efficiency in a practical luminous region (80 to 200
cd/m.sup.2).
SUMMARY OF THE INVENTION
An object of the present invention is to provide an EL device of
high stability and providing a luminance of 1,000 cd/m.sup.2 or
more in blue light region.
Another object of the present invention is to provide an EL device
of high efficiency in a practical luminous region.
Some of the light emitting materials of the present invention are
novel compounds.
Another object of the present invention is to provide such novel
aromatic dimethylidyne compounds.
Another object of the present invention is to provide a process for
efficiently preparing the above novel aromatic dimethylidyne
compound.
That is, the present invention provides an EL device using as a
light emitting material a compound represented by the general
formula: ##STR4## (wherein R.sup.1 and R.sup.2 are each an alkyl
group, a substituted or unsubstituted cyclohexyl group, an alkoxy
group, a cyano group, or a substituted or unsubstituted aryl group,
R.sup.3 and R.sup.4 are each a substituted or unsubstituted
heterocyclic group, or an aryl group, Ar is a substituted or
unsubstituted arylene group, and R.sup.1 and R.sup.3, and R.sup.2
and R.sup.4 may combine together to form a substituted or
unsubstituted, saturated or unsaturated ring structure).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will hereinafter be explained in detail.
In the EL device of the present invention, as a light emitting
material, a compound represented by the general formula: ##STR5##
(wherein R.sup.1 , R.sup.2, R.sup.3, R.sup.4 and Ar have the same
meanings as above) is used.
These compounds have a skeleton similar to that of distyrylbenzene,
have fluorescent properties in a solid state, and have the
characteristics that mobility of electron and positive hole is
good, ionization energy is small owing to the conjugated properties
of the skeleton similar to that of distyrylbenzene, and injection
of electric charge from an electrode, for example, is easy because
of high electron affinity.
In the above general formula (I), R.sup.1 and R.sup.2 are each an
alkyl group, such as a methyl group, an ethyl group, a propyl group
or a butyl group, a substituted or unsubstituted cyclohexyl group,
an alkoxy group, such as a methoxy group, an ethoxy group, a
propoxy group or a butoxy group, a cyano group, or an aryl group.
This aryl group includes phenyl, naphthyl, anthranyl and the like,
and may or may not be substituted by the various groups shown
below. Various substituents can be introduced into the aryl group
as long as they do not deteriorate the above characteristics.
Examples are a halogen atom, an alkyl group such as a methyl group,
an ethyl group, a propyl group or a butyl group, an alkoxy group
such as a methoxy group, an ethoxy group, a propoxy group or a
butoxy group, an acyl group such as a formyl group, an acetyl
group, a propionyl group or a butylyl group, an acyloxy group such
as an acetyloxy group, a propionyloxy group or a butylyloxy group,
an acyl amino group such as acetylamino group, a propionylamino
group or a butylylamino group, an aralkyl group such as a phenoxy
group or a tolyloxy group, a cyano group, a carboxyl group, a vinyl
group, a styryl group, an aminocarbonyl group such as an
anilinocarbonyl group, a dimethylaminocarbonyl group, a carbamoyl
group or an aranyl group, a hydroxyl group, an aryloxycarbonyl
group such as a naphthyloxycarbonyl group, a xylyloxycarbonyl group
or a phenoxycarbonyl group, an alkoxycarbonyl group such as a
methoxycarbonyl group, an ethoxycarbonyl group or a butoxycarbonyl
group, and an amino group represented by the general formula:
##STR6## (wherein R.sup.5 and R.sup.6 are each a hydrogen atom, an
alkyl group such as a methyl group, an ethyl group, a propyl group
or a butyl group, an acyl group such as a formyl group, an acetyl
group or a propionyl group, an aldehyde group, a phenyl group, or a
substituted phenyl group such as a tolyl group or a xylyl group,
and may be the same or different, and may combine together to form
a substituted or unsubstituted 5-membered or 6-membered ring, and
may combine with another group on the aryl group to form a
substituted or unsubstituted, saturated 5-membered ring or
saturated 6-membered ring). R.sup.1 and R.sup.2 may be the same or
different.
Substituents on the aryl group may combine together to form a
substituted or unsubstituted, saturated 5-membered or 6-membered
ring.
R.sup.3 and R.sup.4 in the above general formula (I) are each a
heterocyclic ring or an aryl group such as phenyl, naphthyl or
anthranyl, and may be substituted or unsubstituted. Examples of the
heterocyclic group are a pyridyl group, an oxazolyl group, a
thienyl group, an imidazolyl group, a thiazolyl group, a
benzoimidazolyl group, a benzothiazolyl group, a pyrazolyl group, a
triazolyl group, a monovalent group comprising pyridone, a furaryl
group, a benzoxazolyl group, and a quinolyl group. Substituents
which the aryl group or the heterocyclic ring can have are the same
as those cited above for the aryl group of R.sup.1 and R.sup.2.
R.sup.3 and R.sup.4 may be the same or different.
R.sup.1 and R.sup.3 may combine together to form a substituted or
unsubstituted, saturated or unsaturated ring structure, and R.sup.2
and R.sup.4 may combine together to form a substituted or
unsubstituted, saturated or unsaturated ring structure.
Ar in the above general formula (I) is an arylene group and may be
substituted or unsubstituted. As the substituents, various groups
may be introduced within a range that does not deteriorate the
above characteristics. Examples are a halogen atom, an alkyl group
such as a methyl group, an ethyl group, a propyl group, a butyl
group or a cyclohexyl group, an alkoxy group such as a methoxy
group, an ethoxy group, a propoxy group or a butoxy group, an acyl
group such as a formyl group, an acetyl group, a propionyl group or
a butyryl group, an acyloxy group such as an acetyloxy group, a
propionyloxy group, or a butylyloxy group, an aralkyl group such as
a benzyl group or a phenethyl group, an aryloxy group such as a
phenoxy group or a tolyloxy group, a cyano group, a carboxyl group,
an aminocarbonyl group such as an anilinocarbonyl group, a
dimethylaminocarbonyl group, a carbamoyl group or an aranyl group,
a hydroxyl group, an aryloxycarbonyl group such as a
phenoxycarbonyl group, a naphthyloxycarbonyl group or a
xylyloxycarbonyl group, a methoxycarbonyl group, an ethoxycarbonyl
group, a butoxycarbonyl group, and the amino groups represented by
the above general formula (I).
Substituents on the arylene group may combine together to form a
substituted or unsubstituted, saturated 5-membered or 6-membered
ring.
The compounds represented by the above general formula (I) can be
prepared by various methods; for example, the Wittig method is
suitable.
Representative examples of the compounds represented by the general
formula (I) are shown below. ##STR7##
The novel aromatic dimethylidyne compound of the present invention
is represented by the general formula (II): ##STR8##
This aromatic dimethylidyne compound contains an arylene group
(Ar') in the center thereof and also two substituents (X, Y) at
both terminals which are symmetrical with respect to the central
arylene group.
X and Y in the general formula (II) may be, as described above, the
same or different and are independently an alkyl group having 1 to
4 carbon atoms (a methyl group, an ethyl group, a n-propyl group,
an i-propyl group, a n-butyl group, an i-butyl group, a sec-butyl
group, and a tert-butyl group), a phenyl group, a cyclohexyl group,
a naphthyl group, or a pyridyl group. X and Y may be substituted;
that is, X and Y further represent substituted phenyl groups,
substituted cyclohexyl groups, substituted naphthyl group, or
substituted pyridyl groups. In these groups, the substituent is an
alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to
4 carbon atoms, or a phenyl group. The above substituted groups may
be substituted by two or more substituents. Thus the substituted
phenyl group includes an alkyl group-substituted phenyl group
(e.g., a tolyl group, a dimethylphenyl group, or an ethylphenyl
group), an alkoxy-substituted phenyl group (e.g., a methoxyphenyl
group or an ethoxyphenyl group), and phenyl-substituted phenyl
group (i.e., a biphenyl group). The substituted cyclohexyl group
includes an alkyl group-substituted cyclohexyl group (e.g., a
methylcyclohexyl group, a dimethylcyclohexyl group, or an
ethylcyclohexyl group), an alkoxy group-substituted cyclohexyl
group (e.g., a methoxycyclohexyl group, or an ethoxycyclohexyl
group), and a phenyl group-substituted cyclohexyl group
(phenylcyclohexyl group). The substituted naphthyl group includes
an alkyl group-substituted naphthyl group (e.g., a methylnaphthyl
group, or a dimethylnaphthyl group), an alkoxy group-substituted
naphthyl group (e.g., a methoxynaphthyl group, or an ethoxynaphtyl
group), and a phenyl group-substituted naphthyl group. The
substituted pyridyl group includes an alkyl group-substituted
pyridyl group (e.g., a methyl pyridyl group, a dimethylpyridyl
group, or an ethylpyridyl group), an alkoxy group-substituted
pyridyl group (e.g., a methoxypyridyl group, or an ethoxypyridyl
group), and a phenyl group-substituted pyridyl group.
X and Y are preferred to be independently a methyl group, a phenyl
group, a naphthyl group, a pyridyl group, a cyclohexyl group, a
tolyl group, a methoxyphenyl group, or a biphenyl group.
Ar' in the general formula (II) is an alkyl-substituted arylene
group, including a methyl-substituted arylene group, an
ethyl-substituted arylene group, a propyl-substituted arylene
group, and a butyl-substituted arylene group. Examples are shown
below. ##STR9##
The novel aromatic dimethylidyne compound of the present invention
as described above can be prepared by various methods: it can be
prepared with efficiency particularly by the process A or B of the
present invention.
In accordance with the process A of the present invention, an
arylene group-containing phosphorus compound represented by the
aforementioned general formula (III): ##STR10## (wherein R is an
alkyl group having 1 to 4 carbon atoms and Ar' is the same as
defined above) and a ketone compound represented by the general
formula (IV): ##STR11## (wherein X' and Y' are the same as X and Y
defined above, respectively, provided that an alkyl group having 1
to 4 carbon atoms are excluded) is condensed to prepare the desired
aromatic dimethylidyne compound of the general formula (II').
##STR12## (wherein X', Y' and Ar' are the same as defined
above).
Ar' in the general formula (III) corresponds to Ar' of an aromatic
dimethylidyne compound to be prepared. R is an alkyl group having 1
to 4 carbon atoms (e.g., a methyl group, an ethyl group, a propyl
group, or a butyl group).
This arylene group-containing phosphorus compound can be obtained
by a known method, such as by reacting an aromatic bishalomethyl
compound represented by the general formula:
(wherein X.sup.2 is a halogen atom, and Ar' is the same as defined
above) and trialkyl phosphite represented by the general
formula:
(wherein R is the same as defined above).
In the ketone compound of the general formula (IV), X.sup.1 and
Y.sup.1 are chosen corresponding to X.sup.1 and Y.sup.1 of an
aromatic dimethylidyne compound to be prepared. X.sup.1 and Y.sup.1
are the same as X and Y as described above (excluding an alkyl
group having 1 to 4 carbon atoms).
A condensation reaction of an arylene group-containing phosphorus
compound of the general formula (III) and a ketone compound of the
general formula (IV) can be carried out under various
conditions.
Preferred examples of solvents which can be used in the above
reaction are hydrocarbons, alcohols and ether. Representative
examples are methanol, ethanol, isopropanol, butanol, 2-methoxy
ethanol, 1,2-dimethoxy ethanol, bis(2-methoxyethyl) ether, dioxane,
tetrahydrofuran, toluene, xylene, dimethylsulfoide,
N,N-dimethylformamide, N-methylpyrrolidone, and
1,3-dimethyl-2-imidazolidinone. Of these solvents, tetrahydrofuran
is particularly preferred.
In the reaction, as a condensing agent, sodium hydroxide, potassium
hydroxide, sodium amide, sodium hydride, n-butyl lithium, or
alcolate such as sodium methylate or potassium tert-butoxide is
used if necessary. Of these compounds, n-butyl lithium is
preferred.
The reaction temperature varies with the type of the starting
material and other conditions, and cannot be determined
unconditionally. Usually the reaction temperature is chosen from a
wide range of about 0.degree. to 100.degree. C., with the range of
10.degree. to 70.degree. C. being particularly preferred.
The aromatic dimethylidynes of the present invention can be
prepared efficiently by the above process A. Some of the aromatic
dimethylidyne compounds can be prepared efficiently also by the
process B.
In accordance with the process B, a phosphorus compound of the
general formula (V): ##STR13## (wherein X, Y and R are the same as
defined above) and a dialdehyde compound of the general formula
(VI):
(wherein Ar' is the same as defined above) are subjected to a
condensation reaction to prepare the objective aromatic
dimethylidyne compound of the general formula (II).
In the general formula (V), R is an alkyl group having 1 to 4
carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,
or a butyl group). X and Y are correspondent to X and Y of an
aromatic dimethylidyne compound to be prepared.
In the general formula (VI), Ar' corresponds to Ar' of an aromatic
dimethylidyne compound to be prepared.
The condensation reaction of a phosphorus compound of the general
formula (V) and a dialdehyde compound of the general formula (VI)
can be carried out under various conditions. Solvents and
condensing agents preferably used in the reaction are the same as
in the process A.
The reaction temperature varies with the type of the starting
material and other conditions, and cannot be determined
unconditionally. Usually the reaction temperature is chosen from a
wide range of about 0.degree. to 100.degree. C., with the range of
0.degree. C. to room temperature being particularly preferred.
The aromatic dimethylidyne compounds of the present invention can
be prepared efficiently by the process A and also by the process
B.
The aromatic dimethylidyne compound of the present invention can be
utilized in production of an EL device capable of emitting light of
high luminance at a low voltage.
The aromatic dimethylidyne compound of the present invention
possesses an electric charge injection function, an electric charge
transport function, and a light emitting function which are
essential for a light emitting material of an EL device, and
furthermore is excellent in heat resistance and thin film forming
properties.
Moreover the aromatic dimethylidyne compound of the present
invention has the advantages of being free from decomposition or
degradation even if heated to its vapor deposition temperature,
forming a uniform and dense film, and being free from formation of
pinholes. Thus they can be suitably used in various devices other
than the EL device.
The aromatic dimethylidyne compound of the present invention is, as
described above, effectively used as light emitting materials of an
EL device. This light emitting layer can be produced by forming a
thin film of light emitting material, for example, by forming a
thin film of a compound of the general formula (I) or (II) by known
techniques such as a vacuum evaporation method, a spin coating
method, or a casting method. It is particularly preferred that the
compound of the general formula (I) or (II) be formed into a
molecular accumulated film. The molecular accumulated film as used
herein refers to a thin film formed by depositing a compound from
the gaseous state, or a thin film formed by solidification from the
solution or liquid state. An example of the molecular accumulated
film is a vacuum evaporated film. Usually the molecular accumulated
film can be distinguished from a thin film (molecular accumulated
film) formed by a LB method.
The light emitting layer can be formed by dissolving a binder, such
as a resin, and the compound in a solvent to prepare a solution,
and forming the solution into a thin film by a spin coating
method.
The thickness of the thin film as the light emitting layer as thus
formed is not critical and can be determined appropriately. Usually
the thickness is chosen from a range of 5 nm to 5 .mu.m.
The light emitting layer of the organic EL device is required to
have, for example, (1) an injection function to inject a hole from
a positive electrode or a hole injection layer, and to inject an
electron from a negative electrode or an electron injection layer,
upon application of an electric field, (2) a transport function to
move the charge injected (electron and positive hole) by the force
of electric field, and (3) a light emitting function to provide a
field for recombination of an electron and a hole, thereby causing
light emission.
Although ease of injection of hole and ease of injection of
electron may be different from each other, and the transport
abilities of hole and electron as indicated by their mobilities may
be different from each other, it is preferred that one of the
charges be transported.
Since the ionization potential of the compound of the general
formula (I) to be used in the light emitting layer is usually less
than about 6.0 eV, positive holes can be injected relatively easily
by choosing a proper metal or compound as the positive electrode.
Since the electron affinity of the compound of the general formula
(I) is larger than about 2.8 eV, if a proper metal or compound is
chosen as the negative electrode, electrons can be injected
relatively easily, and moreover an ability to transport electrons
and holes is excellent. Moreover, the compound of the general
formula (I) has a great ability to convert an excited state formed
in the compound, or its associated compound, or its crystal at the
time of re-combination of electron and hole, into light, because it
has strong fluorescence in a solid state.
In connection with the structure of the EL device using the
aromatic dimethylidyne compound of the present invention, there are
various embodiments. Basically the EL device comprises a pair of
electrodes (positive electrode and negative electrode) and the
above light emitting layer sandwiched therebetween, with a hole
injection layer and an electron injection layer being inserted if
necessary. Specific examples of the structures are: (1) positive
electrode/light emitting layer/negative electrode; (2) positive
electrode/hole injection layer/light emitting layer/negative
electrode; and (3) positive electrode/hole injection layer/light
emitting layer/electron injection layer/negative electrode.
Although the hole injection layer and the electron injection layer
are not always needed, they markedly increase light emitting
performance if provided.
The EL device of the above structure is preferably supported on a
substrate. There are no special limitations to the substrate;
substrates commonly used in production of EL devices, such as
glass, transparent plastics, or quartz can be used.
As the positive electrode of the EL device, an electrode made of a
metal, an alloy, an electrically conductive compound or a mixture
thereof, having a large work function (at least about 4 eV) is
preferably used. Specified examples of such materials for the
electrode include metals, e.g., Au, and electrically conductive
transparent compounds, e.g., CuI, ITO, SnO.sub.2, and ZnO. The
positive electrode can be produced by forming a thin film of the
above material by a method such as vacuum evaporation or
sputtering. For light emission from the electrode, it is preferred
that the transmittance be more than 10%, and the sheet resistance
as an electrode be less than several hundred ohms per millimeter
(.OMEGA./.quadrature.). The film thickness is usually from 10 nm to
1 .mu.m and preferably from 10 to 200 nm, although it varies with
the type of the material used.
As the negative electrode, an electrode made of a metal, an alloy,
an electrically conductive compound or a mixture thereof, having a
small work function (less than about 4 eV) is used. Specific
examples of such materials for the negative electrode include
sodium, a sodium-potassium alloy, magnesium, lithium, a
magnesium/second metal mixture, Al/AlO.sub.2, and indium. The
negative electrode can be produced by forming a thin film of the
above material by a method such as vacuum evaporation (vacuum
deposition) or sputtering. The sheet resistance as an electrode is
preferably less than several hundred ohms per millimeter
(.OMEGA./.quadrature.), and the film thickness is usually 10 nm to
1 .mu.m and preferably 50 to 200 nm.
In the EL device, the positive electrode or the negative electrode
is preferably transparent or translucent, in view of a high
efficiency of withdrawing light emitted, because a transparent or
translucent electrode transmits light.
In connection with the structure of the EL device using the
aromatic dimethylidyne compound of the present invention, as
described above, there are a variety of embodiments. In the EL
device of the above structures (2) and (3), the hole injection
layer (positive hole injection transport layer) is a layer of a
hole transporting compound and has a function to transport a hole
injected from the positive electrode to the light emitting layer.
If the hole injection layer is placed between the positive
electrode and the light emitting layer, more holes are injected
into the light emitting layer at a lower electric field and,
moreover, electrons injected from the negative electrode or the
electron injection layer into the light emitting layer are
accumulated in the vicinity of interface between the hole injection
layer and the light emitting layer in the light emitting layer when
the positive hole injection layer does not have electron transport
capability, thereby increasing a luminous efficiency. Thus a device
excellent in light emitting performance is obtained.
As the hole transporting compound to be used in the above hole
injection layer, a compound capable of transporting holes properly
when placed between two electrodes between which an electric field
is applied, and the holes are injected from the positive electrode,
and having a hole mobility of at least 10.sup.-6 cm.sup.2 /V.sec
when an electric field of 10.sup.4 to 10.sup.6 V/cm is applied is
suitably used.
There are no special limitations to the hole transporting compound
as long as it has preferred properties as described above. Known
compounds conventionally used as hole transporting material in
photoconductive materials, or used in the hole injection layer of
the EL device can be used.
Electric charge transporting materials which can be used include
triazole derivatives (described in U.S. Pat. No. 3,112,197, etc.),
oxadiazole derivatives (described in U.S. Pat. No. 3,189,447,
etc.), imidazole derivatives (described in Japanese Patent
Publication No. 16096/1962, et.), polyaryl alkane derivatives
(described in U.S. Pat. Nos. 3,615,402, 3,820,989, 3,542,544,
Japanese Patent Publication Nos. 555/1970, 10983/1976, Japanese
Patent Application Laid-Open Nos. 93224/1976, 17105/1980,
4148/1981, 108667/1980, 156953/1980, 36656/1981, etc.), pyrazoline
derivatives and pyrazolone derivatives (described in U.S. Pat. Nos.
3,180,729, 4,278,746, 88064/1980, 88065/1980, 105537/1974,
51086/1980, 80051/1981, 88141/1981, 45545/1982, 112637/1979,
74546/1980, etc.), phenylenediamine derivatives (described in U.S.
Pat. No. 3,615,404, Japanese Patent Publication Nos. 10105/1976,
3712/1971, 25336/1972, Japanese Patent Application Laid-Open Nos.
53435/1979, 110536/1979, 119925/1979, etc.), arylamine derivatives
(described in U.S. Pat. Nos. 3,567,450, 3,180,703, 3,240,597,
3,658,520, 4,232,103, 4,175,961, 4,012,376, Japanese Patent
Publication Nos. 35702/1974, 27577/1964, Japanese Patent
Application Laid-Open Nos. 144250/1980, 119132/1981, 22437/1981,
West German Patent 1,110,518, etc.), amino substituted calcon
derivatives (described in U.S. Pat. No. 3,526,501, etc.), oxazole
derivatives (described in U.S. Pat. No. 3,257,203, etc.),
styrylanthracene derivatives (described in Japanese Patent
Application Laid-Open No. 46234/1981, etc.), fluorenone derivatives
(described in Japanese Patent Application Laid-Open No.
110837/1979, etc.), hydrazone derivatives (described in U.S. Pat.
No. 3,717,462, Japanese Patent Application Laid-Open Nos.
59143/1979, 52063/1980, 52064/1980, 46760/1980, 85495/1980,
11350/1972, 148749/1972, etc.), stilbene derivatives (described in
Japanese Patent Application Laid-Open Nos. 210363/1986,
228451/1986, 14642/1986, 72255/1986, 47646/1987, 36674/1987,
10652/1987, 30255/1987, 93445/1985, 94462/1985, 174749/1985,
175052/1985, etc.), and the like.
Although these compounds can be used as hole transporting
compounds, porphyrin compounds (described in Japanese Patent
Application Laid-Open No. 295695/1978, etc.) and aromatic tertiary
amine compounds as described hereinafter, and styrylamine compounds
(described in U.S. Pat. No. 4,127,412, Japanese Patent Application
Laid-Open Nos. 27033/1978, 58445/1979, 149631/1979, 64299/1979,
79450/1980, 144250/1980, 119132/1981, 295558/1986, 98353/1986,
295695/1978, etc.) are preferably used. Of these compounds, the
aromatic tertiary amine compounds are particularly preferred.
Typical examples of the porphyrin compound are porphyrin, copper
(II) 1,10,15,20-tetraphenyl-21H,23H-porphyrin, zinc (II)
1,10,15,20-tetraphenyl-21H,23H-porphyrin,
5,10,15,20-tetrakis(pentaflurophenyl)-21H,23H-porphyrin,
siliconphthalocyanine oxide, aluminum phthalocyanine chloride,
phthalocyanine (no metal), dilithium phthalocyanine, copper
tetramethylphthalocyanine, copper phthalocyanine, chromium
phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium
phthalocyanine oxide, magnesium phthalocyanine, and copper
octamethylphthalocyanine.
Typical examples of the aromatic tertiary amine compound and the
styrylamine compound are
N,N,N',N'-tetraphenyl-4,4'-diaminobiphenyl,
N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diaminobiphenyl,
2,2-bis(4-di-p-tolylaminophenyl)propane,
1-bis(4-di-p-tolylaminophenyl)cyclohexane,
N,N,N',N'-tetra-p-tolyl-4,4'-diaminobiphenyl,
1,1-bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane,
bis(4-dimethylamino-2-methylphenyl)phenylmethane,
bis(4-di-p-tolylaminophenyl)phenylmethane,
N,N'-diphenyl-N,N'-di(4-methoxyphenyl)-4,4'-diaminobiphenyl,
N,N,N',N'-tetraphenyl-4,4'-diaminodiphenyl ether,
4,4'-bis(diphenylamino) quadriphenyl, N,N,N-tri(p-tolyl)amine,
4-(di-p-tolylamine)- 4'-[4(di-p-tolyamine)styryl]stilbene,
4-N,N-diphenylamino-(2-diphenylvinyl)benzene,
3-methoxy-4'-N,N-diphenylaminostilbene, and N-phenylcarbozole.
The hole injection layer of the above EL device may be a single
layer of one or more of the above hole transporting compounds, or
may be a laminate of a layer of one or more of the above hole
transporting compounds, and a layer of other hole transporting
compounds.
The electron injection layer (electron injection transport layer)
in the EL device of the above structure (3) is made of an electron
transporting compound and has a function to transport electrons
injected from the negative electrode to the light emitting
layer.
There are no special limitations to the electron transporting
compound to be used; a suitable one selected from the
conventionally known compounds can be used.
Preferred examples of the electron transporting compound include
nitro-substituted fluorenone derivatives having the formulas:
##STR14## thiopyrandioxide derivatives having the formula:
diphenoquinone derivative having the formula: (described in Polymer
Preprints, Japan, Vol, 37, No. 3, p. 681 (1988)), compounds having
the formula: ##STR15## (described in Journal of Applied Physics,
Vol. 27, p. 269 (1988) etc.), anthraquinonodimethane derivatives
(described in Japanese Patent Application Laid-Open Nos.
149259/1982, 55450/1983, 225151/1986, 233750/1986, 104061/1988,
etc.), fluoroenyldenemethane derivatives (described in Japanese
Patent Application Laid-Open Nos. 69657/1985, 143764/1986,
148159/1986, etc.), anthrone derivatives (described in Japanese
Patent Application Laid-Open Nos. 225151/1976, 233750/1986, etc.),
and a compound having the formula: ##STR16##
A suitable example of the process for production of an EL device
using an aromatic dimethylidyne compound of the present invention
will hereinafter be explained.
First, a process for production of an EL device comprising positive
electrode/light emitting layer/negative electrode as described
above is explained.
A thin film of a desired electrode material, for example, a
substance for positive electrode is formed on a suitable substrate
in a thickness of not more than 1 .mu.m, preferably 10 to 200 nm by
a method such as vacuum evaporation or sputtering to provide a
positive electrode. On this positive electrode, a thin film of a
compound of the general formula (I) as a light emitting material is
formed to provide a light emitting layer. For production of the
thin film of the light emitting material, a spin coating method, a
costing method, or a vacuum evaporation method, for example, can be
employed. Of these methods, the vacuum evaporation method is
preferred in that a uniform film can be easily obtained, and
pinholes are less formed.
When the vacuum evaporation method is employed in formation of the
thin film of the light emitting material, although vacuum
evaporation conditions vary with the type of the organic compound
to be used in the light emitting layer, the crystal structure of
the molecular accumulated film, the associate structure, and so on,
the method is desirably carried out under such conditions that the
boat heating temperature is 100.degree. to 350.degree. C., the
degree of vacuum is 10.sup.-5 to 10.sup.-2 Pa, the rate of vacuum
evaporation is 0.01 to 50 nm/sec, the substrate temperature is
-50.degree. C. to +300.degree. C., and the film thickness is 5 nm
to 5 .mu.m.
After formation of the light emitting layer, a thin film of a
substance for negative electrode is formed in a thickness of not
more than 1 .mu.m, preferably 50 to 200 nm by a method such as
vacuum evaporation or sputtering to provide a negative electrode.
In this manner, the desired EL device is obtained.
In this formation of the EL device, the order can be reversed; that
is, the EL device can be produced in the order of negative
electrode, light emitting layer, and positive electrode.
Next, a process for production of an EL device comprising positive
electrode/hole injection layer/light emitting layer/negative
electrode is explained.
A positive electrode is formed in the same manner as in the above
EL device, and a thin film of a hole transporting compound is
formed on the positive electrode by a vacuum evaporation method,
for example, to provide a hole injection layer. This vacuum
evaporation can be carried out under the same conditions as in
formation of the thin film of the light emitting material.
Then, on the hole injection layer, a light emitting layer and a
negative electrode are provided in the same manner as in production
of the above EL device. In this manner, the desired EL device is
obtained.
Also in this formation of the EL device, the order of production
can be reversed; that is, the EL device can be produced in the
order of negative electrode, light emitting layer, hole injection
layer, and positive electrode.
Finally, a process for production of an EL device comprising
positive electrode/hole injection layer/light emitting
layer/electron injection layer/negative electrode is explained.
In the same manner as in production of the above EL device, a
positive electrode, a hole injection layer, and a light emitting
layer are provided in this order. On this light emitting layer, a
thin film of an electron transporting compound is formed by a
vacuum evaporation method, for example, to provide an electron
injection layer. Then, on the electron injection layer, a negative
electrode is provided in the same manner as in production of the
above EL device. In this manner, the desired EL device is
obtained.
Also in this formation of the EL device, the order of production
can be reversed; that is, the EL device can be produced in the
order of negative electrode, light emitting layer, positive hole
injection layer, and positive electrode.
In a case where a DC voltage is applied to the EL device as
obtained above, when a voltage of 3 to 40 V is applied with the
polarity of positive electrode as + and the polarity of negative
electrode as -, light emission is observed from the side of the
transparent or translucent electrode. Even if, however, a voltage
is applied in the reverse polarity, no current flows and light
emission is not observed at all.
In a case where an AC voltage is applied, light emission is
observed only when the positive electrode is + and the negative
electrode is -. In this case, the wave form of the AC voltage
applied is not critical.
The organic EL device of the present invention provides EL light
emission at a luminance of several hundred cd/m.sup.2 in the region
of bluish purple to green and at a luminance of at least 1,000
cd/m.sup.2 in the region of blue to green, and at the same time, to
obtain efficient EL light emission of more than 0.5 lm/W at a
luminance of a practical level (50 to 200 cd/m.sup.2).
Moreover, the novel aromatic dimethylidyne compounds of the present
invention are expected to be effectively utilized as various
functional materials, utilizing their properties such as electron
transporting properties, luminescence properties, electron
injection properties, and thin film properties.
The present invention is described in greater detail with reference
to the following examples.
EXAMPLE 1
(1) Preparation of Arylene Group-Containing Phosphorus Compound
8.0 g of 1,4-bis(chloromethyl)benzene and 13.0 g of trimethyl
phosphite were stirred for 4 hours while heating at a temperature
of 150.degree. C. on an oil bath in a stream of argon gas.
Then, excessive trimethyl phosphite and methyl chloride by-produced
were distilled away under reduced pressure. When the residue was
allowed to stand for one night, 10.0 g of white crystal was
obtained (yield 68%). The melting point was 65.degree.-70.degree.
C. The results of a proton nuclear magnetic resonance .sup.1
H--NMR) analysis of the white crystal were as follows:
.sup.1 H--NMR (CDCl.sub.3);
.delta.=7.0 ppm (s; 4H, benzene ring --H);
.delta.=3.5 ppm (d; 12H, ester --OCH.sub.3);
.delta.=3.0 ppm (d; J=16 Hz (.sup.31 P--.sup.1 H coupling); 4H,
P--CH.sub.2).
The above results confirmed that the above product was an arylene
group-containing phosphorus compound (phosphonate) having the
following formula: ##STR17##
(2) Preparation of Aromatic Dimethylidyne Compound
5.0 g of the phosphate obtained in (1) above and 5.0 g of
4,4'-dimethylbenzophenone were dissolved in 100 ml of
tetrahydrofuran, and 3.0 g of potassium tert-butoxide was added
thereto. The resulting mixture was stirred for 5 hours at room
temperature in a stream of argon, and was allowed to stand
overnight.
Then, 100 ml of water was added to the above mixture, and
precipitated crystals were filtered off. The crystals were washed
thoroughly with water and then with methanol, and recrystallized
from benzene to obtain 2.0 g of yellowish green crystals (yield
30%). Melting point was 215.0.degree.-216.0.degree. C. The results
of a .sup.1 H--NMR analysis of the crystal are as follows:
.sup.1 H--NMR (CDCl.sub.3)
.delta.=7.0 to 7.2 ppm (m; 16H, p-tolylbenzene ring --H);
.delta.=6.8 ppm (d; 4H, benzene ring --H, d; 2H, methylidyne
--CH.dbd.C--);
.delta.=2.3 ppm (d; 12H, p-tolylmethyl group --CH.sub.3).
By a direct type mass spectrum (MS), a molecular ion peak m/Z=490
of the desired product was detected.
The results of an elemental analysis (as C.sub.38 H.sub.34) were as
follows. The values in the parentheses indicate theoretical
values.
C: 93.10% (93.07%);
H: 6.90% (6.93%);
N: 0.00% (0%);
In an infrared ray (IR) absorption spectral (KBr tablet method)
analysis, absorptions due to stretch vibration of C.dbd.C were
observed at 1520 cm.sup.-1 and 1620 cm.sup.-1.
The above results confirmed that the above product, yellowish green
crystal, was a 1,4-phenylenedimethylidyne derivative having the
following formula: ##STR18##
EXAMPLES 2 TO 5
The 1,4-phenylenedimethylidyne derivatives shown in Table 1 were
prepared in the same manner as in Example 1 (2) except that the
ketones shown in Table 1 were used in place of
4,4'-dimethylbenzophenone.
TABLE 1 IR Composition Melt- Absorption Formula ing Spectrum
Structural Formula of (molecular Point (KBr Elemental Analysis (%)
No. Ketone Aromatic Dimethylidyne Compound weight) (.degree.C.)
.sup.1 H-NMR (CDCl.sub.3, TMS) Properties tablet) (theoretical
value) Ex-am-ple2 ##STR19## ##STR20## C.sub.34 H.sub.26(434.34)
193.0to193.5 .delta. = 7.2 ppm (s;20H, terminal aromatic ring
H).delta. = 6.8 ppm (d;4H, central benzenering H) (d;2H,
methylidyne CHC) YellowishGreenPowder .nu..sub.c=c1510
cm.sup.-11620 cm.sup.-1 C 94.32 (94.01)H 6.04 ( 5.99)N 0.00 ( 0) a
Ex-m-ple3 ##STR21## ##STR22## C.sub.36 H.sub.30(462.36)
117.0to118.5 .delta. = 7.0 to 7.4 ppm(m;18H, terminal aromaticring
H).delta. = 6.85 ppm (d;4H, central benzenering H)(d;2H,
methylidyne CHC).delta. 2.4 ppm (d;6H, p-tolylmethyl CH.sub.3)
YellowishGreenPowder .nu..sub.c=c1520 cm.sup.-1 1610 cm.sup.-1 C
93.30 (93.51)H 6.23 ( 6.49)N 0.00 ( 0) Ex-am-ple4 ##STR23##
##STR24## C.sub.34 H.sub.38(446.34) 175.0to177.0 .delta. = 6.8 to
7.2 ppm(m;18H, terminal aromaticring H).delta. = 6.4 ppm (s;4H,
central benzenering H).delta. = 6.1 ppm (s;2H, methylidyne
CHC).delta. = 1 to 2 ppm(m;22H, cyclohexyl H) WhitePowder
.nu..sub.c=c1520 cm.sup.-11620 cm.sup.-1 C 91.68 (91.49)H 8.47 (
8.51)N 0.00 ( 0) Ex-am-ple5 ##STR25## ##STR26## C.sub.36 H.sub.30
O.sub.2(494.36) 162.0to164.0 .delta. = 6.8 to 7.3 ppm(m;20H,
terminal aromaticring H).delta. = 6.8 ppm (m;4H, central
benzenering H)(m;2H, methylidyne CHC).delta. = 3.8 ppm (s;6H,
methoxy group OCH.sub.3) YellowishGreenPowder .nu..sub.c=c1520
cm.sup.-11610 cm.sup.-1 C 87.24 (87.46)H 6.24 ( 6.07)N 0.00 (
0)
EXAMPLE 6
(1) Preparation of Arylene Group-Containing Phosphorus Compound
25 g of 2,5-bis(chloromethyl)xylene and 45 g of triethyl phosphite
were stirred while heating at 150.degree. C. for 7 hours on an oil
bath in a stream of argon.
Then, excessive triethyl phosphite and ethyl chloride by-produced
were distilled away under reduced pressure. After allowing to stand
overnight, 50 g of white crystal (quantitatively) was obtained.
Melting point: 59.0.degree.-60.5.degree. C. The results of a .sup.1
H--NMR analysis were as follows.
.sup.1 H--NMR (CDCl.sub.3);
.delta.=6.9 ppm (s; 2H, central xylene ring --H);
.delta.=3.9 ppm (q; 8H, ethoxy group methylene --CH.sub.2);
.delta.=3.1 ppm (d; 4H, J=20 Hz (.sup.31 P--.sup.1 H coupling)
P--CH.sub.2);
.delta.=2.2 ppm (s; 6H, xylene ring --CH.sub.3);
.delta.=1.1 ppm (t; 12H, ethoxy group methyl --CH.sub.3).
The above results confirmed that the above product was an arylene
group-containing phosphorus compound (phosphonate) having the
following formula: ##STR27##
(2) Preparation of Aromatic Dimethylidyne Compound
5.3 g of the phosphonate obtained in (1) above and 5.2 g of
2-benzoylbiphenyl were dissolved in 100 ml of tetrahydrofuran, and
12.3 g of a hexane solution containing n-butyllithium
(concentration 15%) was added. The resulting mixture was stirred at
room temperature for 6 hours in a stream of argon, and was allowed
to stand overnight.
To the mixture thus obtained was added 300 ml of methanol, and
precipitated crystals were filtered off. The filtered product was
thoroughly washed three times with 100 ml of water and then three
times with 100 ml of methanol to obtain 5.5 g of light yellow
powder (yield 44%). The melting point was 187.degree.-188.degree.
C. The results of a .sup.1 H--NMR analysis of the powder were as
follows:
.sup.1 H--NMR (CDCl.sub.3);
.delta.=7.7 to 7.0 ppm (m; 30H, aromatic ring);
.delta.=6.7 ppm (s; 2H, methylidyne --CH.dbd.C--);
.delta.=2.0 ppm (s; 6H, xylene ring --CH.sub.3).
The results of elemental analysis (Composition Formula C.sub.48
H.sub.38) were as follows. The values in the parentheses were
theoretical values.
C: 93.79% (93.82%);
H: 6.06% (6.18%);
N: 0.00% (0%).
An infrared ray (IR) absorption spectrum (KBr method) was as
follows:
The above results confirmed that the above product, light yellow
powder was a 2,5-xylenedimethylidyne derivative having the
following formula: ##STR28##
EXAMPLE 7 TO 12
The 2,5-xylenedimethylidyne derivatives shown in Table 2 were
prepared in the same manner as in Example 6 (2) except that the
ketones were used in place of 2-benzoylbiphenyl.
TABLE 2 Compo- sition IR Formula Absorption (mole- Melting Spectrum
Structural Formula of cular Point (KBr Elemental Analysis (%) No.
Ketone Aromatic Dimethylidyne Compound weight) (.degree. C.) .sup.1
H-NMR (CDCl.sub.3, TMS) Properties tablet) (theoretical value)
Ex-am-ple7 ##STR29## ##STR30## C.sub.34 H.sub.26(434.34) 242to243.5
.delta. = 6.9 to 7.1 ppm(m;16H, terminal tolylgroup benzene ring
H).delta. = 6.7 ppm (s;2H, central xylenering H).delta. = 6.5 ppm
(s;2H, methylidyne CCH).delta. = 2.3 ppm (s;12H, terminal
tolylgroup CH.sub.3).delta. = 2.0 ppm (s;6H, central xylenering
CH.sub.3) LightYellowPowder .nu..sub.c=c1510 cm.sup.-11620
cm.sup.-1 C 92.60 (92.67)H 7.23 ( 7.33)N 0.00 ( 0) Ex-am-ple8
##STR31## ##STR32## C.sub.44 H.sub.34(562.44) 199to205 .delta. =
7.0 to 7.8 ppm(m;24H, aromatic ring).delta. = 7.0 ppm (s;2H,
central xylenering H).delta. = 6.6 ppm (s;2H, methylidyne
CCH).delta. = 2.0 ppm (s;6H, central xylenering CH.sub.3)
LightYellowPowder .nu..sub.c =c1510 cm.sup.-11620 cm.sup.-1 C 93.87
(93.95)H 5.82 ( 6.05)N 0.00 ( 0) Ex-am-ple9 ##STR33## ##STR34##
C.sub.38 H.sub.46 O.sub.2(534.48) 172to174 .delta. = 6.2 to 7.2
ppm(m;12H, terminal benzene ring,xylene ring H, and
methylidyneCCH).delta . = 3.8 ppm (s;6H, methoxy group
OCH.sub.3).delta. = 1.9 ppm (s;6H, central xylene
ringCH.sub.3).delta. = 0.8 to 0.2 ppm(b;22H, cyclohexane ring)
LightYellowPowder .nu..sub.c=c1520 cm.sup.-11620 cm.sup.-1 C 85.06
(85.39)H 8.82 ( 8.61)N 0.00 ( 0) Ex-am-ple10 ##STR35## ##STR36##
C.sub.34 H.sub.28 N.sub.2(464.34) 192to192.5 .delta. = 7.0 to 8.5
ppm(m;20H, terminal benzenering H, central xylene ring H,and
pyridine ring).delta. = 6.5 ppm (s;2H, methylidyne CCH).delta. =
2.0 ppm (s;6H, central ring CH.sub.3) YellowPowder .nu..sub.c=c1510
cm.sup.-11610 cm.sup.-1 C 87.79 (87.94)H 5.90 ( 6.03)N 0.00 ( 0)
Ex-am-ple11 ##STR37## ##STR38## C.sub.36 H.sub.42(474.36)
177.5to179 ##STR39## WhitePowder .nu..sub.c=c1520 cm.sup.-11620
cm.sup.-1 C 91.02 (91.15)H 8.89 ( 8.85)N 0.00 ( 0) CH.sub.3)
.delta. = 1.0 to 2.0 ppm (b;22H, cyclohexane ring) Ex-am-ple12
##STR40## ##STR41## C.sub.42 H.sub.54(558.89) 166to167 .delta. =
6.5 to 6.9 ppm(m;12H, aromatic ring H).delta. = 2.8 ppm (m;2H,
isopropyl group CH).delta. = 1.8 ppm (s;6H, central xylene
ringCH.sub.3).delta. = 1.2 ppm (d;12H, isopropyl
groupCH.sub.3).delta. = 1.0 to 2.0 ppm(b;22H, cyclohexane ring)
WhitePowder .nu..sub.c=c1520 cm.sup.-11620 cm.sup.-1 C 90.15
(90.26)H 9.69 ( 9.74)N 0.00 ( *Value of mass spectrum, m/Z = 534
**Value of mass spectrum, m/Z = 464 ***Value of mass spectrum, m/Z
= 558. iPr indicates an isopropyl group.
EXAMPLE 13
(1) Preparation of Phosphorus Compound
25.1 g of (1-bromoethyl)benzene and 24.7 g of triethyl phosphite
were heated with stirring at 150.degree. C. for 7 hours on an oil
bath in a stream of argon. Then, excessive triethyl phosphite and
bromoethyl by-produced were distilled away under reduced pressure
to obtain 22.3 g of a transparent solution. The results of a .sup.1
H--NMR analysis were as follows:
.delta.=7.2 ppm (s; 5H, benzene ring --H)
.delta.=3.9 ppm (q; 4H, ethoxy group --OCH.sub.2 --);
.delta.2.9 to 3.5 ppm (m; .sup.1 H, .dbd.CH--);
.delta.1.0 to 2.0 ppm (m; 9H, methyl of ethoxy and --CH.sub.3).
The above results confirmed that the above product was a phosphorus
compound (phosphonate) having the following formula: ##STR42##
(2) Preparation of Aromatic Dimethylidyne Compound
9.7 g of the phosphonate obtained in (1) above and 3.0 g of
terephthalaldehyde were dissolved in 100 ml of tetrahydrofuran, and
3.0 g of a hexane solution containing n-butyl lithium
(concentration 15%) was added thereto. The resulting mixture was
stirred for 5 hours at room temperature in a stream of argon, and
then was allowed to stand overnight.
To the mixture above obtained, 100 ml of methanol was added, and
precipitated crystals were filtered off. The filtered product was
thoroughly washed three times with 100 ml of water and then three
times with 100 ml of methanol to obtain 1.3 g of white flaky
crystals (yield 20%). Melting point was 179.degree.-180.degree. C.
The results of a .sup.1 H--NMR analysis of the crystal were as
follows.
.sup.1 H--NMR (CDCl.sub.3);
.delta.=7.2 to 7.5 ppm (m; 14H, benzene ring --H);
.delta.=6.8 ppm (s; 2H, methylidyne --CH.dbd.C--);
.delta.=2.3 ppm (s; 6H, methyl group).
The results of elemental analysis (as composition formula, C.sub.24
H.sub.22) were as follows. The values in the parentheses are
theoretical values.
C: 92.84% (92.91%);
H: 7.23% (7.09%);
N: 0.00% (0%);
In a mass spectrum, a molecular ion peak m/Z=310 of the desired
product was detected.
The above results confirmed that the above product of white flaky
crystal was a 1,4-phenylenedimethylidyne derivative having the
following formula: ##STR43##
EXAMPLE 14
A 2,5-xylenedimethylidyne derivative having the formula: ##STR44##
was prepared in the same manner as in Example 13 (2) except that
2,5-xylenedicarboxyaldehyde was used in place of
terephthalaldehyde.
Analytical results were as follows:
Melting point, 137.0.degree.-137.8.degree. C.
.sup.1 H--NMR (CDCl.sub.3);
.delta.=6.8 to 7.5 ppm (m; 14H, benzene ring --H, central xylene
ring --H, methylidyne --CH.dbd.C--);
.delta.=2.3 ppm (s: 6H, terminal methyl group --CH.sub.3);
.delta.=2.1 ppm (s; 6H, central xylene ring --CH.sub.3);
Shape: white powder.
Elemental Analysis (as composition formula C.sub.26 H.sub.26). The
values in the parentheses are theoretical values.
C: 92.26% (92.31%);
H: 7.50% (7.69%);
N: 0.00% (0%).
EXAMPLE 15
(1) Preparation of Arylene Group-Containing Phosphorus Compound
9.0 g of 4,4'-bis(bromomethyl)biphenyl and 11 g of triethyl
phosphite were heated with stirring at 140.degree. C. for 6 hours
on an oil bath in a stream of argon.
Then, excessive triethyl phosphite and ethyl bromide by-produced
were distilled away under reduced pressure. After allowing to stand
overnight, 9.5 g of white crystals were obtained yield 80%). The
melting point was 97.0.degree.-100.0.degree. C. The results of a
.sup.1 H--NMR analysis were as follows:
.sup.1 H--NMR (CDCl.sub.3):
.delta.=7.0 to 7.6 ppm (m; 8H, biphenylene ring --H);
.delta.=4.0 ppm (q; 8H, ethoxy group methylene --CH.sub.2);
.delta.=3.1 ppm (d; 4H, J=20 Hz (.sup.31 P--.sup.1 H coupling)
P--CH.sub.2);
.delta.=1.3 ppm (t; 12H, ethoxy group methyl --CH.sub.3).
The above results confirmed that the above product was an arylene
group-containing phosphorus compound (phosphonate) having the
following formula: ##STR45##
(2) Preparation of Aromatic Dimethylidyne Compound
4.0 g of the phosphonate obtained in (1) above and 5.0 g of
cyclohexyl phenyl ketone were dissolved in 60 ml of dimethyl
sulfoxide, 2.0 g of potassium tert-butoxide was added, and the
resulting mixture was stirred under reflux in a stream of argon and
then was allowed to stand overnight.
After removal by distillation of the solvent from the above
mixture, 200 ml of methanol was added, and precipitated crystals
were filtered off. The filtered product was thoroughly washed three
times with 100 ml of water and then three times with 100 ml of
methanol, and then recrystallized from benzene to obtain 1.0 g of
light yellow powder (yield 22%). The melting point was
153.degree.-155.degree. C. The results of a .sup.1 H--NMR analysis
of the powder were as follows:
.sup.1 H--NMR (CDCl.sub.3):
.delta.=6.3 to 7.5 ppm (b; 18H, aromatic ring and methylidyne
--CH.dbd.C--);
.delta.=1.0 to 2.0 ppm (b; 22H, cyclohexane ring).
The results of elemental analysis (as composition formula C.sub.40
H.sub.42) were as shown below. The values in the parentheses are
theoretical values.
C: 91.74% (91.90%);
H: 8.25% (8.10%);
N: 0.00% (0%).
The results of an infrared ray (IR) absorption spectrum (KBr tablet
method) were as follows:
In a mass spectrum, a molecular ion peak m/Z=522 of the desired
product was detected.
The above results confirmed that the above product was a
4,4'-biphenylenedimethylidyne derivative having the following
formula: ##STR46##
EXAMPLE 16
A 4,4'-biphenylenedimethylidyne derivative having the following
formula: ##STR47## was prepared in the same manner as in Example 15
(2) except
that 4,4'-dimethylbenzophenone was used in place of cyclohexyl
phenyl ketone, and tetrahydrofuran, in place of dimethyl
sulfoxide.
The analytical results were as shown below.
Melting point: 228.degree.-230.degree. C..
.sup.1 H--NMR (CDCl.sub.3):
.delta.=6.7 to 7.3 ppm (m; 26H, aromatic ring --H and methylidyne
--CH.dbd.C--):
.delta.=2.4 ppm (s; 12H, p-tolylmethyl group --CH.sub.3).
Shape: light yellow powder.
Molecular ion peak of mass spectrum: m/Z=566.
Elemental analysis: as shown below (as composition formula,
C.sub.44 H.sub.38). The values in the parentheses are theoretical
values.
C: 93.10% (93.24%);
H: 7.04% (6.76%);
N: 0.00% (0%);
EXAMPLE 17
(1) Preparation of Arylene Group-Containing Phosphorus Compound
24.3 g of 2,6-bis(bromomethyl)naphthalene and 50 g of triethyl
phosphite were heated with stirring at 120.degree. C. for 7 hours
on an oil bath in a stream of argon.
Then, excessive triethyl phosphite and ethyl bromide by-produced
were distilled away under reduced pressure. After allowing to stand
overnight, 32.5 g of light yellow crystals were obtained (yield,
quantitatively). The melting point was 144.5.degree.-146.0.degree.
C. The results of a .sup.1 H--NMR analysis were as shown below.
.sup.1 H--NMR (CDCl.sub.3):
.delta.=7.2 to 7.8 ppm (m; 6H, naphthylene ring --H);
.delta.=4.0 ppm (q; 8H, ethoxy group methylene --CH.sub.2);
.delta.=3.3 ppm (d; 4H, J=20 Hz (31P--.sup.1 H coupling);
P--CH.sub.2);
.delta.=1.2 ppm (t; 12H, ethoxy group methyl --CH.sub.3).
The above results confirmed that the above product was an arylene
group-containing phosphorus compound (phosphonate) having the
following formula: ##STR48##
(2) Preparation of Aromatic Dimethylidyne Compound
5.0 g of the phosphonate obtained in (1) above and 5.0 g of
cyclohexyl phenyl ketone were dissolved in 100 ml of
tetrahydrofuran, 2.5 g of potassium tert-butoxide was added
thereto, and the resulting mixture was stirred under reflux in a
stream of argon and then was allowed to stand overnight.
After removal by distillation of the solvent from the mixture above
obtained, 100 ml of methanol was added, and precipitated crystals
were filtered off. The filtered product was thoroughly washed twice
with 100 ml of water and then twice with 100 ml of methanol, and
then recrystallized from benzene to obtain 1.0 g of light yellow
powder (yield 20%). The melting point was 215.degree.-216.degree.
C. The results of a .sup.1 H--NMR analysis of the powder were as
shown below.
.sup.1 H--NMR (CDCl.sub.3):
.delta.=6.2 to 7.2 ppm (m; 18H, aromatic ring and naphthalene ring
--H, and methylidyne --CH.dbd.C--);
.delta.=1.0 to 2.0 ppm (b; 22H, cyclohexane ring).
The results of elemental analysis (as composition formula C.sub.38
H.sub.40) were as shown below. The values in the parentheses are
theoretical values.
C: 91.63% (91.88%);
H: 8.20% (8.12%);
N: 0.00% (0%).
The above results confirmed that the above product, light yellow
powder was a 2,6-naphthylenedimethylidyne derivative having the
following formula: ##STR49##
EXAMPLE 18
A 2,6-naphthylenedimethylidyne derivative having the following
formula: ##STR50## was prepared in the same manner as in Example 17
(2) except that 4,4'-dimethylbenzophenone was used in place of
cyclohexyl phenyl ketone, and n-butyl lithium, in place of
potassium tert-butoxide.
The analytical results are shown below.
Melting point: 269.degree.-271.degree. C.
.sup.1 H--NMR (CDCl.sub.3);
.delta.=6.7 to 7.2 ppm (m; 24H, aromatic ring --H and methylidyne
--CH.dbd.C--);
.delta.=2.4 ppm (s; 12H, p-tolylmethyl group --CH.sub.3).
Shape: yellow powder.
Elemental analysis: as shown below (as composition formula C.sub.42
H.sub.36). The values in the parentheses are theoretical
values.
C: 93.03% (93.29%);
H: 6.81% (6.71%);
N: 0.00% (0%).
EXAMPLE 19
(1) Preparation of Arylene Group-Containing Phosphorus Compound
10 g of 9,10-bis(chloromethyl)anthracene and 35 g of triethyl
phosphite were heated with stirring at 130.degree. C. for 6 hours
on an oil bath in a stream of argon.
Then, excessive triethyl phosphite and ethyl chloride by-produced
were distilled away under reduced pressure. After allowing to stand
overnight, light green crystals were obtained, and the crystals
were then recrystallized from benzene-hexane to obtain 16 g of
light yellow flaky crystals (yield 92%).
The analytical results are shown below.
Melting point: 160.degree.-161.5.degree. C.
.sup.1 H--NMR (CDCl.sub.3):
.delta.=7.3 to 8.4 ppm (m; 8H, anthracene ring --H);
.delta.=4.1 ppm (d; 4H, J=20 Hz (31P--.sup.1 H coupling)
P--CH.sub.2);
.delta.=3.7 ppm (q; 8H; ethoxy group methylene --CH.sub.2);
.delta.=1.0 ppm (t; 12H, ethoxy group methyl --CH.sub.3).
The above results confirmed that the above product was an arylene
group-containing phosphorus compound (phosphonate) having the
following formula: ##STR51##
(2) Preparation of Aromatic Dimethylidyne Compound
3.0 g of the phosphonate obtained in (1) above and 2.5 g of
4,4'-dimethylbenzophenone were dissolved in 100 ml of
tetrahydrofuran, 5 g of a hexane solution containing n-butyl
lithium (concentration 15%) was added thereto, and the resulting
mixture was stirred for 4 hours at room temperature in a stream of
argon and then was allowed to stand overnight.
To the mixture obtained above, 100 ml of methanol was added, and
precipitated crystals were filtered off. The filtered product was
thoroughly washed three times with 100 ml of water and then three
times with 100 ml of methanol, and then recrystallized from toluene
to obtain 0.7 g of yellowish orange powder (yield 19%).
The analytical results are shown below.
Melting point: 297.degree.-298.degree. C.
.sup.1 H--NMR (CDCl.sub.3):
.delta.=6.5 to 7.5 ppm (m; 26H, aromatic ring --H, anthracene --H,
and methylidyne --CH.dbd.C--);
.delta.=2.2 ppm (d; 12H, p-tolylmethyl group --CH.sub.3).
Elemental analysis: As shown below as composition formula C.sub.46
H.sub.38. The values in the parentheses indicates theoretical
values.
C: 93.42% (93.52%);
H: 6.53% (6.48%);
N: 0.00% (0%).
In a mass spectrum, a molecular ion peak m/Z=590 of the desired
product was detected.
The above results confirmed that the above product, yellowish
orange powder, was a 9,10-anthracenediyldimethylidyne derivative
having the following formula: ##STR52##
EXAMPLE 20
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick film of ITO provided on the glass
substrate by a vacuum evaporation method (produced by HOYA Co.,
Ltd.) was used as a transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available evaporation system (manufactured by ULVAC
Co., Ltd.). In an electrically heated boat made of molybdenum, 200
mg of
N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine
(TPDA) was placed, and in the other boat of molybdenum, 200 mg of a
1,4-phenylenedimethylidyne derivative,
1,4-bis(2,2-di-p-tolylvinyl)benzene (DTVB), was placed. The
pressure of the vacuum chamber was decreased to 1.times.10.sup.-4
Pa.
The boat in which TPDA was placed was heated to 215.degree. to
220.degree. C., and TPDA was vapor deposited (vacuum deposited) on
the transparent substrate at a deposition speed of 0.1 to 0.3
nm/sec to form a hole injection layer with a film thickness of 60
nm. The temperature of the substrate at this time was room
temperature.
Then, without taking the substrate out of the vacuum chamber, DTVB
was vacuum deposited from the other boat in a 80 nm laminate film
form as a light emitting layer. In connection with vacuum
deposition conditions, the temperature of the boat was 237.degree.
to 238.degree. C., the vacuum deposition speed was 0.1 to 0.3
nm/sec, and the substrate temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer, and was
then attached to the substrate holder.
Then, 1 g of magnesium ribbon was placed on an electrically heated
boat made of molybdenum, and in the other electrically heated boat
made of molybdenum, 500 mg of indium was placed. The pressure of
the vacuum chamber was decreased 2.times.10.sup.4 Pa. Then, the
indium was vacuum deposited at a vacuum deposition speed of 0.03 to
0.08 nm/sec, and at the same time, magnesium in the other boat was
vacuum deposited at a vacuum deposition speed of 1.7 to 2.8 nm/sec.
The temperature of the boat containing indium was 800.degree. C.,
and the temperature of the boat containing magnesium was
500.degree. C.
Under the above conditions, a magnesium-indium mixed metal
electrode was vacuum deposited in a thickness of 150 nm on the
light emitting layer as an opposite electrode to thereby produce a
device.
Upon application of a DC voltage of 20 V onto the above device with
the ITO electrode as a positive electrode and the magnesium-indium
mixed metal electrode as a negative electrode, a current of about
100 mA/cm.sup.2 flew and the emitted light was blue green in the
chromaticity coqrdinates. The wavelength of the peak as determined
by spectrometer was 486 nm. The maximum luminance was 1,000
cd/m.sup.2.
EXAMPLE 21
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (manufactured by
ULVAC Co., Ltd.). In an electrically heated boat made of
molybdenum, 200 mg of TPDA was placed, and in the other boat, 200
mg of the 1,4-phenylenedimethylidyne derivative obtained in Example
2, 1,4-bis(2,2-di-phenylvinyl)benzene (DPVB), was placed. The
pressure of the vacuum chamber was decreased to 1.times.10.sup.-4
Pa.
Then, the above boat in which TPDA was placed was heated to
215.degree. to 220.degree. C., and TPDA was vacuum deposited at a
vacuum deposition speed of 0.1 to 0.3 nm/sec on the transparent
substrate to thereby produce a hole injection layer with a film
thickness of 60 nm. At this time, the substrate was at room
temperature.
Then, without taking the substrate out of the vacuum chamber, on
the positive hole injection layer, DPVB was vacuum deposited from
the other boat in a thickness of 80 nm as a light emitting layer.
In connection with the vacuum deposition conditions, the boat
temperature was 152.degree. to 153.degree. C., the vacuum
deposition speed was 0.1 to 0.3 nm/sec, and the substrate
temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and then
attached to the substrate holder.
In an electrically heated boat made of molybdenum, 1 g of magnesium
ribbon was placed, and in the other electrically heated boat made
of molybdenum, 500 mg of indium was placed.
The pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa. Then, indium was vacuum deposited at a vacuum
deposition speed of 0.03 to 0.08 nm/sec, and from the other boat,
magnesium was vacuum deposited at a vacuum deposition speed of 1.7
to 2.8 nm/sec. The temperature of the boat containing indium was
800.degree. C., and the temperature of the boat containing
magnesium was 500.degree. C.
Under the above conditions, a magnesium-indium mixed metal
electrode was vacuum deposited on the light emitting layer as the
opposite electrode to thereby produce a device.
Upon application of a DC voltage of 10 V onto the device with the
ITO electrode as a positive electrode and the magnesium-indium
mixed metal electrode as a negative electrode, a current of about
1.1 mA/cm.sup.2 flew, and a luminance of 50 cd/m.sup.2 was
obtained. At this time, luminous efficiency was 1.2 lm/W.
Furthermore, upon application of a DC voltage of 17.5 V, a current
of about 75 mA/cm.sup.2 flew, and the emitted light was greenish
blue in the chromaticity coordinates. The wavelength of the peak
was 483 nm, and the maximum luminance was 1,000 cd/m.sup.2.
EXAMPLE 22
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (manufactured by
ULVAC Co., Ltd.). In an electrically heated boat made of
molybdenum, 200 mg of TPDA was placed, and in the other boat made
of molybdenum, 200 mg of the 1,4-phenylenedimethylidyne derivative
obtained in Example 3, 1,4-bis(2-phenyl-2-p-tolyl)benzene (PTVB)
was placed. The pressure of the vacuum chamber was decreased to
1.times.10.sup.-4 Pa.
The boat containing TPDA was heated to 215.degree. to 220.degree.
C., and TPDA was vacuum deposited on the transparent substrate at a
vacuum deposition speed of 0.1 to 0.3 nm/sec to thereby produce a
hole injection layer with a film thickness of 60 nm. At this time,
the substrate was at room temperature.
Without taking the substrate out of the vacuum chamber, PTVB was
vacuum deposited on the hole injection layer from the other boat in
a thickness of 80 nm as a light emitting layer. In connection with
vacuum deposition conditions, the boat temperature was about
200.degree. C., the vacuum deposition speed was 0.2 to 0.4 nm/sec,
and the substrate temperature was room temperature. The substrate
was taken out of the vacuum chamber, and a stainless steel mask was
placed on the above light emitting layer and again attached to the
substrate holder.
In an electrically heated boat made of molybdenum, 1 g of magnesium
ribbon was placed, and in the other electrically heated boat made
of molybdenum, 500 mg of indium was placed.
The pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa. Then, indium was vacuum deposited at a speed
of 0.03 to 0.08 nm/sec, and at the same time, from the other boat,
magnesium was vacuum deposited at a speed of 1.7 to 2.8 nm/sec. The
temperature of the boat containing indium was 800.degree. C., and
the temperature of the boat containing magnesium was 500.degree.
C.
Under the above conditions, a magnesium-indium mixed metal
electrode was vacuum deposit in a laminated form in a thickness of
150 nm on the light emitting layer to thereby produce a device.
Upon application of a DC voltage of 20 V onto the device above
obtained, with an ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 100 mA/cm.sup.2 flew, and the emitted light was
greenish blue in the chromaticity coordinates. The wavelength of
the peak as determined by spectral measurement was 486 nm, and the
maximum luminance was 700 cd/m.sup.2.
EXAMPLE 23
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). Then, 200 mg of TPDA was placed in an electrically
heated boat made of molybdenum, and in the other boat made of
molybdenum, 200 mg of the 1,4-phenylenedimethylidyne derivative
obtained in Example 4, 1,4-bis(2-phenyl-2-cyclohexyl vinyl)benzene
(PCVB), was placed. The pressure of the vacuum chamber was
decreased to 1.times.10.sup.-4 Pa.
Then, the above boat containing TPDA was heated to 215.degree. to
220.degree. C., and vacuum deposited on the transparent substrate
at a vacuum deposition speed of 0.1 to 0.3 nm/sec to form a 60 nm
thick hole injection layer. At this time, the substrate temperature
was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, PCVB was vacuum deposited on the hole injection layer
in a laminated form in a thickness of 80 nm. In connection with
vacuum deposition conditions, the boat temperature was 185.degree.
to 190.degree. C., the vacuum deposition temperature was 0.1 to 0.3
nm, and the substrate temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and again
attached to the substrate holder.
In an electrically heated boat made of molybdenum, 1 g of magnesium
ribbon was placed, and in the other electrically heated boat made
of molybdenum, 500 mg of indium was placed.
After the pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa, indium was vacuum deposited at a vacuum
deposition speed of 0.03 to 0.08 nm/sec, and from the other boat,
magnesium was vacuum deposited at a vacuum deposition speed of 1.7
to 2.8 nm/sec. The temperature of the boat containing indium was
800.degree. C., and the temperature of the boat containing
magnesium was 500.degree. C.
Under the above conditions, a magnesium-indium mixed metal
electrode was vacuum deposited on the light emitting layer in a
laminated form in a thickness of 150 nm to form the opposite
electrode, thereby producing a device.
Upon application of a DC voltage of 20 V onto the device above
obtained, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 3.5 mA/cm.sup.2 flew, and bluish purple light was
emitted. The wavelength of the peak was 425 nm as determined by
spectral measurement. The luminance was 50 cd/m.sup.2, and
sufficient light emission was confirmed in a light place.
EXAMPLE 24
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). Then, 200 mg of TPDA was placed in an electrically
heated boat made of molybdenum, and in the other boat made of
molybdenum, 200 mg of the 1,4-bis
[2-(p-methoxyphenyl)-2-phenylvinyl]benzene (MEPVB) obtained in
Example 5 was placed. The pressure of the vacuum chamber was
decreased to 1.times.10.sup.-4 Pa.
Then the above boat containing TPDA was heated to 215.degree. to
220.degree. C. and vacuum deposited on the transparent substrate at
a vacuum deposition speed of 0.1 to 0.3 nm/sec to form a 60 nm
thick hole injection layer. At this time, the substrate temperature
was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, MEPVB was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum conditions, the boat temperature
was 107.degree. C., the vacuum deposition speed was 0.4 to 0.6
nm/sec, and the substrate temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and again
attached to the substrate holder.
Then, in an electrically heated boat made of molybdenum, 1 g of
magnesium ribbon was placed, and in the other electrically heated
boat made of molybdenum, 500 mg of indium was placed.
After the pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa, indium was vacuum deposited at a vacuum
deposition speed of 0.03 to 0.08 nm/sec, and from the other boat,
magnesium was vacuum deposited at a vacuum deposition speed of 1.7
to 2.8 nm/sec. The temperature of the boat containing indium was
800.degree. C., and the temperature of the boat containing
magnesium was 500.degree. C. Under the above conditions, a
magnesium-indium mixed metal electrode was vacuum deposited on the
light emitting layer in a thickness of 150 nm in a laminated form
to form the opposite electrode, thereby producing a device.
Upon application of a DC voltage of 12 V onto the device above
obtained, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 160 mA/cm.sup.2 flew, and the emitted light was
blue green in the chromaticity coordinates, and the luminance was
700 cd/m.sup.2.
EXAMPLE 25
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). Then, 200 mg of TPDA was placed in an electrically
heated boat made of molybdenum, and in the other boat made of
molybdenum, 200 mg of the 2,5-xylenedimethylidyne derivative
obtained in Example 6, 2,5-bis(2-phenyl-2-biphenylvinyl)xylene
(BPVX) was placed. The pressure of the vacuum chamber was decreased
to 1.times.10.sup.-4 Pa.
Then, the above boat containing TPDA was heated to 215.degree. to
220.degree. C. and vacuum deposited at a vacuum deposition speed of
0.1 to 0.3 nm/sec on the transparent substrate to form a 60 nm
thick hole injection layer. At this time, the substrate temperature
was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, BPVX was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emittting
layer. In connection vacuum deposition conditions, the boat
temperature was 184.degree. C., the vacuum deposition speed was 0.2
to 0.4 nm/sec, and the substrate temperature was room
temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and again
attached to the substrate holder.
Then, 1 g of magnesium ribbon was placed in an electrically heated
boat made of molybdenum, and in the other electrically heated boat
made of molybdenum, 500 mg of indium was placed.
Then the pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa. Then, indium was vacuum deposited at a vacuum
deposition of speed of 0.03 to 0.08 nm/sec, and from the other
boat, magnesium was vacuum deposited at a vacuum deposition speed
of 1.7 to 2.8 nm/sec. The temperature of the boat containing indium
was 800.degree. C., and the temperature of the boat containing
magnesium was 500.degree. C. Under the above conditions, a
magnesium-indium mixed metal electrode was vacuum deposited on the
light emitting layer in a thickness of 150 nm in a laminated form
to form the opposite electrode, thereby producing a device.
Upon application of a DC voltage of 20 V onto the device above
obtained, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 170 mA/cm.sup.2 flew, and light emission in bluish
green in the chromaticity coordinates was obtained. The wavelength
of the peak was 499 nm as determined by spectral measurement, and
the luminance was more than 1,000 cd/m.sup.2.
EXAMPLE 26
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO layer provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was subjected to UV ozone cleaning for 2
minutes by the use of a UV ozone treating apparatus (manufactured
by Nippon Battery Co., Ltd.).
The substrate was attached to a substrate holder of a commercially
available vacuum deposition system (produced by ULVAC Co., Ltd.).
Then, 200 mg of TPDA was placed in an electrically heated boat made
of molybdenum, and in the other boat made of molybdenum, 200 mg of
the 2,5-xylenedimethylidyne derivative obtained in Example 7,
2,5-bis(2,2-di-p-tolyvinyl)xylene (DTVX), was placed. The pressure
of the vacuum chamber was decreased to 1.times.10.sup.-4 Pa.
The above boat containing TPDA was heated to 215.degree. to
220.degree. C. and vacuum deposited on the transparent substrate at
a vacuum deposition speed of 0.1 to 0.3 nm/sec to form a 60 nm
thick hole injection layer. At this time, the substrate temperature
was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, DTVX was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 215.degree. C., the vacuum deposition speed was 0.2
to 0.4 nm/sec, and the substrate temperature was room
temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and again
attached to the substrate holder.
In an electrically heated boat made of molybdenum, 1 g of magnesium
ribbon was placed, and in the other electrically heated boat made
of molybdenum, 500 mg of indium was placed.
After the pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa, indium was vacuum deposited at a vacuum
deposition speed of 0.03 to 0.08 nm/sec and at the same time, from
the other boat, magnesium was vacuum deposited at a vacuum
deposition speed of 1.7 to 2.8 nm/sec. The temperature of the boat
containing indium was 800.degree. C., and the temperature of the
boat containing magnesium was 500.degree. C. Under the above
conditions, a magnesium-indium mixed metal electrode was vacuum
deposited on the light emitting layer in a thickness of 150 nm in a
laminated form to form the opposite electrode, thereby producing a
device.
Upon application of a DC voltage of 5 V onto the device obtained
above, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 6.3 mA/cm.sup.2 flew. The luminance of emitted
light was 300 cd/m.sup.2, and the emitted light was greenish blue
in the chromaticity coordinates. The wavelength of the peak was 486
nm. At this time, the luminous efficiency was 2.9 lm/W.
Furthermore, it was confirmed that when a DC voltage of 7 V was
applied, the luminance of emitted light was more than 1,000
cd/m.sup.2.
EXAMPLE 27
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). In an electrically heated boat made of molybdenum, 200
mg of TPDA was placed, and in the other electrically heated boat
made of molybdenum, 200 mg of the 2,5-xylenedimethylidyne
derivative obtained in Example 8,
2,5-bis[2-phenyl-2-(2-naphthyl)vinyl]-xylene (NPVX) was placed. The
pressure of the vacuum chamber was decreased to 1.times.10.sup.-4
Pa.
The boat containing TPDA was heated to 215.degree. to 220.degree.
C., and TPDA was vacuum deposited on the transparent substrate at a
vacuum deposition speed of 0.1 to 0.3 nm to form a 60 nm thick hole
injection layer. At this time, the substrate temperature was room
temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, NPVX was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 147.degree. C., the vacuum deposition speed was 0.2
to 0.4 nm/sec, and the substrate temperature was room
temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and again
attached to the substrate holder.
Then, 1 g of magnesium ribbon was placed in an electrically heated
boat made of molybdenum, and in the other electrically heated boat
made of molybdenum, 500 mg of indium was placed.
After the pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa, indium was vacuum deposited at a vacuum
deposition speed of 0.03 to 0.08 nm/sec, and at the same time, from
the other boat, magnesium was vacuum deposited at a vacuum
deposition speed of 1.7 to 2.8 nm/sec. The temperature of the boat
containing indium was 800.degree. C., and the temperature of the
boat containing magnesium was 500.degree. C. Under the above
conditions, a magnesium-indium mixed metal electrode was vacuum
deposited on the light emitting layer in a thickness of 150 nm in a
laminated form to form the opposite electrode, thereby producing a
device.
Upon application of a DC voltage of 17.5 V onto the device obtained
above, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 220 mA/cm.sup.2 flew, and light emission of bluish
green in the chromaticity coordinates was obtained. The wavelength
of the peak was 502 nm as determined by spectral measurement. The
luminance of emitted light was 1,000 cd/m.sup.2.
EXAMPLE 28
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (manufactured by
ULVAC Co., Ltd.). Then, 200 mg of TPDA was placed in an
electrically heated boat made of molybdenum, and in the other boat
made of molybdenum, 200 mg of the 2,5 -xylenedimethylidyne
derivative obtained in Example 10,
2,5-bis[2-phenyl-2-(2-pyridyl)vinyl]xylene (PPVX), was place. The
pressure of the vacuum chamber was decreased to 1.times.10.sup.-4
Pa.
The above boat containing TPDA was heated to 215.degree. to
220.degree. C., and TPDA was vacuum deposited on the transparent
substrate at a vacuum deposition speed of 0.1 to 0.3 nm/sec to form
a 60 nm thick hole injection layer. At this time, the substrate
temperature was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, PPVX was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 198.degree. C., the vacuum deposition speed was 0.2
to 0.4 nm/sec, and the substrate temperature was room
temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and again
attached to the substrate holder.
Then, in an electrically heated boat made of molybdenum, 1 g of
magnesium ribbon was placed, and in the other electrically heated
boat made of molybdenum, 500 mg of indium was placed.
After the pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa, indium was vacuum deposited at a vacuum
deposition speed of 0.03 to 0.08 nm/sec, and at the same time, from
the other boat, magnesium was vacuum deposited at a vacuum
deposition speed of 1.7 to 2.8 nm/sec. The temperature of the boat
containing indium was 800.degree. C., and the temperature of the
boat containing magnesium was 500.degree. C. Under the above
conditions, a magnesium-indium mixed metal electrode was vacuum
deposited on the light emitting layer in a thickness of 150 nm in a
laminated form to form the opposite electrode, thereby producing a
device.
Upon application of a DC voltage of 12.5 V onto the device obtained
above, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 50 mA/cm.sup.2 flew, and light emission in green
in the chromaticity coordinates was obtained. The wavelength of the
peak was 531 nm as determined by spectral measurement, and the
luminance was 100 cd/m.sup.2.
EXAMPLE 29
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). Then, 200 mg of TPDA was placed in an electrically
heated boat made of molybdenum, and in the other boat made of
molybdenum, 200 mg of the 2,5-xylenedimethylidyne derivative
obtained in Example 14, 2,5-bis(2-phenyl-2-methylvinyl)xylene
(MePVX), was placed. The pressure of the vacuum chamber was
decreased to 1.times.10.sup.-4 Pa.
The above boat containing TPDA was heated to 215.degree. to
220.degree. C., and TPDA was vacuum deposited on the transparent
substrate at a vacuum deposition speed of 0.1 to 0.3 nm/sec to form
a 60 nm thick hole injection layer. At this time, the substrate
temperature was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, MePVX was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 152.degree. C., the vacuum deposition speed was 0.2
to 0.4 nm/sec, and the substrate temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and again
attached to the substrate holder.
Then, 1 g of magnesium ribbon was placed in an electrically heated
boat made of molybdenum, and in the other electrically heated boat
made of molybdenum, 500 mg of indium was placed. Then, after the
pressure of the vacuum chamber was decreased to 2.times.10.sup.-4
Pa, indium was vacuum deposited at a vacuum deposition speed of
0.03 to 0.08 nm/sec, and at the same time, from the other boat,
magnesium was vacuum deposited at a vacuum deposition speed of 1.7
to 2.8 nm/sec. The temperature of the boat containing indium was
800.degree. C., and the temperature of the boat containing
magnesium was 500.degree. C. Under the above conditions, a
magnesium-indium mixed metal electrode was vacuum deposited on the
light emitting layer in a thickness of 150 nm in a laminated form
to form the opposite electrode, thereby producing a device.
Upon application of a DC voltage of 10 V onto the device obtained
above, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 140 mA/cm.sup.2 flew, and purplish blue light
emission in the chromaticity coordinates was obtained. The
wavelength of the peak was 438 nm as determined by spectral
measurement, and the luminance of emitted light was about 20
cd/m.sup.2.
EXAMPLE 30
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate. This transparent substrate was subjected to
UV ozone cleaning for 2 minutes by the use of a UV ozone cleaning
apparatus.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). Then, 200 mg of TPDA was placed in an electrically
heated boat made of molybdenum, and in the other boat made of
molybdenum, the 4,4'-biphenylenedimethylidyne derivative obtained
in Example 15, 4,4'-bis(2-cyclohexyl-2-phenylvinyl)biphenyl
(CPVBi), was placed. The pressure of the vacuum chamber was
decreased to 1.times.10.sup.-4 Pa.
The boat containing TPDA was heated to 215.degree. to 220.degree.
C., and TPDA was vacuum deposited on the transparent substrate at a
vacuum deposition speed of 0.1 to 0.3 nm/sec to form a 60 nm thick
hole injection layer. At this time, the substrate temperature was
room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, CPVBi was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 210.degree. C., the vacuum deposition speed was 0.1
to 0.3 nm/sec, and the substrate temperature was room
temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the above light emitting layer and again
attached to the substrate holder.
Then, 1 g of magnesium ribbon was placed in an electrically heated
boat made of molybdenum, and in the other electrically heated boat
made of molybdenum, 500 mg of indium was placed.
After the pressure of the vacuum chamber was decreased, indium was
vacuum deposited at a vacuum deposition speed of 0.03 to 0.08
nm/sec, and at the same time, from the other boat, magnesium was
vacuum deposited at a vacuum deposition speed of 1.7 to 2.8 nm/sec.
The temperature of the boat containing indium was 800.degree. C.,
and the temperature of the boat containing magnesium was
500.degree. C. Under the above conditions, a magnesium-indium mixed
metal electrode was vacuum deposited on the light emitting layer in
a thickness of 150 nm in a laminated form to form the opposite
electrode, thereby producing a device.
Upon application of a DC voltage of 7 V onto the device obtained
above, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 14 mA/cm.sup.2 flew, and light emission of
purplish blue in the chromaticity coordinates was obtained. The
wavelength of the peak was 441 nm as determined by spectral
measurement, and the luminance of emitted light was about 200
cd/m.sup.2. The luminous efficiency was 0.64 lm/W.
EXAMPLE 31
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent electrode. This transparent electrode was subjected to
UV ozone cleaning for 2 minutes by the use of a UV ozone cleaning
apparatus.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). Then, 200 mg of TPDA was placed in an electrically
heated boat made of molybdenum, and in the other boat made of
molybdenum, 200 mg of the 4,4'-biphenylenedimethylidyne derivative
obtained in Example 16, 4,4'-bis(2,2-di-p-tolylvinyl)biphenyl
(DTVBi), was placed. The pressure of the vacuum chamber was
decreased to 1.times.10.sup.-4 Pa.
The boat containing TPDA was heated to 215.degree. to 220.degree.
C., and TPDA was vacuum deposited on the transparent substrate at a
vacuum deposition speed of 0.1 to 0.3 nm/sec to form a hole
injection layer with a film thickness of 60 nm. At this time, the
substrate temperature was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, DTVBi was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 253.degree. to 271.degree. C., the vacuum
deposition speed was 0.1 to 0.3 nm/sec, and the substrate
temperature was room temperature. The substrate was taken out of
the vacuum chamber. A stainless steel mask was placed on the above
light emitting layer and again attached to the substrate
holder.
Then, 1 g of magnesium ribbon was placed in an electrically heated
boat made of molybdenum, and in the other electrically heated boat
made of molybdenum, 500 mg of indium was placed.
After the pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa, indium was vacuum deposited at a vacuum
deposition speed of 0.03 to 0.08 nm/sec, and at the same time, from
the other boat, magnesium was vacuum deposited at a vacuum
deposition speed of 1.7 to 2.8 nm. The temperature of the boat
containing indium was 800.degree. C., and the temperature of the
boat containing magnesium was 500.degree. C. Under the above
conditions, a magnesium-indium mixed metal electrode was vacuum
deposited on the light emitting layer in a thickness of 150 nm in a
laminated form to form the opposite electrode, thereby producing a
device.
Upon application of a DC voltage of 15 V onto the device obtained
above, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 32 mA/cm.sup.2 flew, and light emission of blue in
the chromaticity coordinates was obtained. The wavelength of the
peak was 473 nm, and the maximum luminance of emitted light was
more than 1,000 cd/m.sup.2. The efficiency was more than 0.65
lm/W.
EXAMPLE 32
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate. This transparent substrate was subjected to
UV ozone cleaning for 2 minutes by the use of a UV ozone cleaning
apparatus.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). Then, 200 mg of TPDA was placed in an electrically
heated boat made of molybdenum, and in the other boat made of
molybdenum, 200 mg of the 2,6-naphthylenedimethylidyne derivative
obtained in Example 18, 2,6-bis(2,2-di-p-tolylvinyl)naphthalene
(DTVN), was placed. The pressure of the vacuum chamber was
decreased to 1.times.10.sup.-4 Pa.
The boat containing TPDA was heated to 215.degree. to 220.degree.
C., and TPDA was vacuum deposited on the transparent substrate at a
vacuum deposition speed of 0.1 to 0.3 nm/sec to form a 60 nm thick
hole injection layer. At this time, the substrate temperature was
room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, DTVN was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 276.degree. to 278.degree. C., the vacuum
deposition speed was 0.1 to 0.3 nm/sec, and the substrate
temperature was room temperature. The substrate was taken out of
the vacuum chamber. A stainless steel mask was placed on the above
light emitting layer and again attached to the substrate
holder.
Then, 1 g of magnesium ribbon was placed in an electrically heated
boat made of molybdenum, and in the other electrically heated boat
made of molybdenum, 500 mg of indium was placed.
After the pressure of the vacuum chamber was decreased to
2.times.10.sup.-4 Pa, indium was vacuum deposited at a vacuum
deposition speed of 0.03 to 0.08 nm/sec, and at the same time, from
the other boat, magnesium was vacuum deposited at a vacuum
deposition speed of 1.7 to 2.8 nm/sec. The temperature of the boat
containing indium was 800.degree. C., and the temperature of the
boat containing magnesium was 500.degree. C. Under the above
conditions, a magnesium-indium mixed metal electrode was vacuum
deposited on the light emitting layer in a thickness of 150 nm in a
laminated form to form the opposite electrode, thereby producing a
device.
Upon application of a DC voltage of 12 V onto the device obtained
above, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 350 mA/cm.sup.2 flew, and light emission of
greenish blue in chromaticity coordinates was obtained. The
wavelength of the peak was 486 nm as determined by spectral
measurement, and the luminance of emitted light was 20
cd/m.sup.2.
EXAMPLE 33
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method (manufactured by HOYA Co., Ltd.) was used as a
transparent substrate. This transparent substrate was subjected to
UV ozone cleaning for 2 minutes by the use of a UV ozone cleaning
apparatus.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (produced by ULVAC
Co., Ltd.). Then, 200 mg of TPDA was placed in an electrically
heated boat made of molybdenum, and in the other boat made of
molybdenum, 200 mg of the 9,10-anthracenedimethylidyne derivative
obtained in Example 19, 9,10-bis(2,2-di-p-tolylvinyl)anthracene
(DTVA), was placed. The pressure of the vacuum chamber was
decreased to 1.times.10.sup.-4 PA.
The boat containing TPDA was heated to 215.degree. to 220.degree.
C., and TPDA was vacuum deposited on the transparent substrate at a
vacuum deposition speed of 0.1 to 0.3 nm/sec to form a 60 nm thick
hole injection layer. At this time, the substrate temperature was
room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, DTVA was vacuum deposited on the hole injection layer
in a thickness of 80 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 270.degree. C., the vacuum deposition speed was 0.1
to 0.3 nm/sec, and the substrate temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the light emitting layer and again
attached to the substrate holder.
Then, 1 g of magnesium ribbon was placed in an electrically heated
boat made of molybdenum, and in the other electrically heated boat
made of molybdenum, 500 mg of indium was placed. After the pressure
of the vacuum chamber was decreased to 2.times.10.sup.-4 Pa, indium
was vacuum deposited at a vacuum deposition speed of 0.03 to 0.08
nm/sec, and at the same time, from the other boat, magnesium was
vacuum deposited at a vacuum deposition speed of 1.7 to 2.8 nm/sec.
The temperature of the boat containing indium was 800.degree. C.,
and the temperature of the boat containing magnesium was
500.degree. C. Under the above conditions, a magnesium-indium mixed
metal electrode was vacuum deposited on the light emitting layer in
a thickness of 150 nm in a laminated form to form the opposite
electrode, thereby producing a device.
Upon application of a DC voltage of 10 V onto the device obtained
above, with the ITO electrode as a positive electrode and the
magnesium-indium mixed metal electrode as a negative electrode, a
current of about 350 mA/cm.sup.2 flew, and light emission of green
in the chromaticity coordinates was obtained. The wavelength of the
peak was 526 nm as determined by spectral measurement, and the
luminance of emitted light was more than 400 cd/m.sup.2.
EXAMPLE 34
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method was used as a transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (manufactured by
ULVAC Co., Ltd.). Then, 200 mg of TPDA was placed in an
electrically heated boat made of molybdenum, and in the other boat
made of molybdenum, 200 mg of DPVB was placed. The pressure of the
vacuum chamber was decreased to 1.times.10.sup.-4 Pa.
The boat containing TPDA was heated to 215.degree. to 220.degree.
C., and TPDA was vacuum deposited on the transparent substrate at a
vacuum deposition speed of 0.1 to 0.3 nm/sec to form a 75 nm thick
hole injection layer. At this time, the substrate temperature was
room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, DPVB was vacuum deposited on the hole injection layer
in a thickness of 60 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 152.degree. to 153.degree. C., the vacuum
deposition speed was 0.1 to 0.2 nm/sec, and the substrate
temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the light emitting layer and again
attached to the substrate holder. Then, 1 g of magnesium ribbon was
placed in an electrically heated boat made of molybdenum, and as an
electron gun target for electron beam vacuum deposition, positioned
under the substrate holder in the central part of the vacuum
chamber, copper pellets were placed. After the pressure of the
vacuum chamber was decreased to 2.times.10.sup.-4 Pa, copper was
vacuum deposited at a vacuum deposition speed of 0.03 to 0.08
nm/sec by an electron beam vacuum deposition method, and at the
same time, from the molybdenum boat, magnesium was vacuum deposited
at a vacuum deposition speed of 1.7 to 2.8 nm/sec by an
electrically heating method. At this time, the emission current of
a filament of the electron gun was 200.degree. to 30 mA, the
acceleration voltage was 4 kV, and the boat temperature was about
500.degree. C. Under the above conditions, a magnesium-copper mixed
metal electrode was vacuum deposited on the light emitting layer in
a thickness of 70 nm in a laminated form to form the opposite
electrode.
Upon application of a DC voltage of 19 V on the EL device produced
above, with the ITO electrode as a positive electrode and the
magnesium-copper mixed metal electrode as a negative electrode, a
current of 91 mA/cm.sup.2 flew, and light emission of bluish green
was obtained. The wavelength of the peak was 491 nm as determined
by spectral measurement, and the luminance of the emitted light was
880 cd/m.sup.2.
The light emission was uniformly in the plane light emission, and
it was confirmed that there were no pin holes in the light emitting
layer. Moreover, light emission was greatly stabilized.
EXAMPLE 35
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method was used as a transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (manufactured by
ULVAC Co., Ltd.). Then, 200 mg of TPDA was placed in an
electrically heated boat made of molybdenum, and in the other boat
made of molybdenum, 200 mg of
1,4-bis(2-p-methylphenyl-2-biphenylvinyl)benzene (MPVB) was placed.
The pressure of the vacuum chamber was decreased to
1.times.10.sup.-4 Pa. Then the boat containing TPDA was heated to
215.degree. to 220.degree. C., and TPDA was vacuum deposited on the
transparent substrate at a vacuum deposition speed of 0.1 to 0.3
nm/sec to form a 75 nm thick hole injection layer. At this time,
the substrate temperature was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, MPVB was vacuum deposited on the hole injection layer
in a thickness of 60 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 180.degree. to 190.degree. C., the vacuum
deposition speed was 0.1 to 0.2 nm/sec, and the substrate
temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the light emitting layer and again
attached to the substrate holder. Then, 1 g of magnesium ribbon was
placed in an electrically heated boat made of molybdenum, and as an
electron gun target for electron beam vacuum deposition as
positioned under the substrate holder in the central part of the
vacuum chamber, copper pellets were placed. Then, after the
pressure of the vacuum chamber was decreased to 2.times.10.sup.-4
Pa, copper was vacuum deposited at a vacuum deposition speed of
0.03 to 0.08 nm/sec by an electron beam vacuum deposition method,
and at the same time, from the molybdenum boat, magnesium was
vacuum deposited at a vacuum deposition speed of 1.7 to 2.8 nm/sec
by an electrically heating method. At this time, the emission
current of a filament of the electron gun was 200 to 230 mA, the
acceleration voltage was 4 kV, and the boat temperature was about
500.degree. C. Under the above conditions, a magnesium-copper mixed
metal electrode was vacuum deposited on the light emitting layer in
a thickness of 70 nm in a laminated form to form the opposite
electrode.
Upon application of a DC voltage of 20 V onto the EL device
obtained above, with the ITO electrode as a positive electrode and
the magnesium-copper mixed metal electrode as a negative electrode,
a current of 238 mA/cm.sup.2 flew, and light emission of green was
obtained. The wavelength of the peak was 512 nm as determined by
spectral measurement, and the luminance of emitted light was 1,100
cd/m.sup.2.
As in Example 34, light emission was uniform in the light emission
plane, and the light of green was greatly stabilized.
EXAMPLE 36
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method was used as a transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (manufactured by
ULVAC Co., Ltd.). Then, 200 mg of TPDA was placed in an
electrically heated boat made of molybdenum, and in the other boat
made of molybdenum, 200 mg of DTVB obtained in Example 1 was
placed. The pressure of the vacuum chamber was decreased to
1.times.10.sup.-4 Pa. The boat containing TPDA was heated to
215.degree. to 220.degree. C., and TPDA was vacuum deposited on the
transparent substrate at a vacuum deposition speed of 0.1 to 0.3
nm/sec to form a 70 nm thick hole injection layer. At this time,
the substrate temperature was room temperature.
Without taking the substrate out of the vacuum chamber, from the
other boat, DTVB was vacuum deposited on the hole injection layer
in a thickness of 60 nm in a laminated form as a light emitting
layer. In connection with vacuum deposition conditions, the boat
temperature was 237.degree. to 238.degree. C., the vacuum
deposition speed was 0.1 to 0.2 nm/sec, and the substrate
temperature was room temperature.
The substrate was taken out of the vacuum chamber. A stainless
steel mask was placed on the light emitting layer and again
attached to the substrate holder. Then, 1 g of magnesium ribbon was
placed in an electrically heated boat, and as an electron gun
target for electron beam vacuum deposition as posited under the
substrate holder in the central part of the vacuum chamber, copper
pellets were placed. The pressure of the vacuum chamber was
decreased to 2.times.10.sup.-4 Pa. Then, copper was vacuum
deposited at a vacuum deposition speed of 0.03 to 0.08 nm/sec by an
electron beam vacuum deposition method, and at the same time, from
the molybdenum boat, magnesium was vacuum deposited at a vacuum
deposition speed of 1.7 to 2.8 nm/sec. At this time, the emission
current of a filament of the electron gun was 200.degree. to 230
mA, the acceleration voltage was 4 kV, and the boat temperature was
about 500.degree. C. Under the above conditions, a magnesium-copper
mixed metal electrode was vacuum deposited on the light emitting
layer in a thickness of 70 nm in a laminated form to form the
opposite electrode.
Upon application of a DC voltage of 20 V onto the EL device
obtained above, with the ITO electrode as a positive electrode and
the magnesium-copper mixed metal electrode as a negative electrode,
a current of 119 mA/cm.sup.2 flew, and light emission of bluish
green was obtained. The wavelength of the peak was 487 nm as
determined by spectral measurement, and the luminance of the
emitted light was 980 cd/m.sup.2.
The emitted light was uniform in the emitted light plane and was
greatly stable.
EXAMPLE 37
A member comprising a 25 mm.times.75 mm.times.1.1 mm glass
substrate and a 100 nm thick ITO film provided thereon by a vacuum
deposition method was used as a transparent substrate.
This transparent substrate was attached to a substrate holder of a
commercially available vacuum deposition system (manufactured by
ULVAC Co., Ltd.). Then, 200 mg of TPDA was placed in an
electrically heated boat made of molybdenum, and in the other boat
made of molybdenum, 200 mg of DPVB was placed. Then the pressure of
the vacuum chamber was decreased to 1.times.10.sup.-4 Pa. The above
boat containing TPDA was heated to 215.degree. to 220.degree. C.,
and TPDA was vacuum deposited on the transparent substrate at a
vacuum deposition speed of 0.1 to 0.3 nm/sec to form a 60 nm thick
positive hole injection layer. At this time, the substrate
temperature was room temperature.
Then, in the same manner as in Example 34, DPVB was laminated.
The pressure of the vacuum chamber was returned to atmospheric
pressure, and the two boats made of molybdenum were taken out of
the vacuum chamber. Instead, a molybdenum boat containing 200 mg of
[3",4":3,4,5:10",9":3',4',5']-dipyridyno[1,2-a:1',2'-a]bisbenzoimidazole-6
,18-dione was placed in the vacuum chamber. Then the pressure of
the vacuum chamber was decreased to 2.times.10.sup.-4 Pa. The above
boat was heated to 500.degree. C. and the above substance was
vacuum deposited on the light emitting layer in a thickness of 60
nm in a laminated form as an electron injection layer.
The pressure of the vacuum chamber was returned to atmospheric
pressure. After removal of the above laminated sample from the
substrate holder, a stainless steel mask was placed and then
attached to the substrate holder. Then, 1 g of magnesium ribbon was
placed in an electrically heated boat made of molybdenum, and as an
electron gun target for electron beam vacuum deposition as
positioned below the substrate holder in the central part of the
vacuum chamber, a copper pellet was placed. After the pressure of
the vacuum chamber was decreased to 2.times.10.sup.-4 Pa, copper
was vacuum deposited at a vacuum deposition speed of 0.03 to 0.08
nm/sec by the electron beam vacuum deposition method, and at the
same time, magnesium was vacuum deposited at a vacuum deposition
speed of 1.7 to 2.8 nm/sec by the electrically heating method. At
this time, the emission current of a filament of the electron gun
was 200 to 230 mA, the acceleration voltage was 4 kV, and the
temperature of the boat was about 500.degree. C. Under the above
conditions, a magnesium-copper mixed metal electrode was vacuum
deposited on the light emitting layer in a thickness of 100 nm in a
laminated form to form the opposite electrode.
Upon application of a DC voltage of 19 V onto the EL device above
produced, with the ITO electrode as a positive electrode and the
magnesium-copper mixed metal electrode as a negative electrode, a
current of about 100 mA/cm.sup.2 flew, and the same bluish green
light as in Example 34 was emitted. The wavelength of the peak was
490 nm as determined by spectral measurement, and the luminance was
1,000 cd/m.sup.2.
The luminous state was uniform and greatly stabilized as in Example
34.
* * * * *